Understanding the exact amount of grain needed for your mash is crucial for successful brewing. The mash tun weight calculation ensures you have enough grain to achieve your target batch size while accounting for mash thickness and the water absorbed by the grain. This calculation helps brewers avoid under-mashing (leading to lower efficiency) or over-mashing (potentially causing stuck mashes).
This calculator simplifies the process, allowing homebrewers and professional brewers alike to quickly determine the necessary grain quantities. By inputting your desired final beer volume, the preferred mash thickness, and an estimate of your grain's water absorption, you can obtain an accurate grain weight for your mash tun. This is a fundamental step in recipe formulation and brew day planning.
Why is Accurate Grain Weight Important?
Getting the grain weight right impacts several key brewing aspects:
Brewing Efficiency: Too little grain means you won't extract enough sugars from the malt, resulting in a beer with lower alcohol content and body.
Mash Thickness: The ratio of water to grain affects enzyme activity and sugar conversion. The correct thickness ensures optimal conditions for starch conversion.
Mash Tun Capacity: Ensures you don't overfill your mash tun, which can lead to poor lautering and stuck sparge.
Water Management: Knowing the grain weight helps accurately calculate the total water needed for mashing and sparging.
Who Should Use This Calculator?
This calculator is ideal for:
Homebrewers: Planning new recipes, scaling existing ones, or ensuring accuracy on brew day.
Commercial Brewers: Quickly verifying grain quantities for different batch sizes and mash profiles.
Recipe Developers: Formulating new beer recipes with precise measurements.
Common Misconceptions
A common misconception is that grain weight is solely determined by batch size. However, mash thickness (the ratio of water to grain) and the grain's inherent water absorption are critical variables that significantly influence the final required grain amount. Neglecting these can lead to significant inaccuracies. Another misconception is that all grains absorb water equally; while generally similar, variations exist, and accounting for this can refine results.
Mash Tun Grain Weight Formula and Mathematical Explanation
The calculation for determining the required grain weight is based on the principles of mash liquid-to-grain ratios and water absorption.
The Core Formula
The primary formula used is derived as follows:
Let:
B = Desired Batch Size (finished beer volume)
T = Mash Thickness (e.g., quarts per pound or liters per kilogram)
A = Grain Water Absorption (e.g., gallons per pound or liters per kilogram)
G = Total Grain Weight (what we want to find)
W = Total Water Needed for Mash
1. The total volume of the mash (liquor + grain) is often approximated by the desired batch size plus the water absorbed by the grain. However, a more direct approach for calculating grain weight relies on the mash thickness, which defines the ratio of water to grain.
2. Mash Thickness (T) is defined as: Water for Mash (W) / Grain Weight (G). So, W = T * G.
3. The total volume of the mash liquid *before* accounting for absorption is W. After absorption, the volume of liquid remaining is W - (G * A). This remaining liquid volume is what ultimately becomes your batch size (B), plus any losses during the boil. For simplicity in this calculator, we assume the target batch size represents the usable wort after mashing and before boil losses, and the mash thickness is applied to achieve this.
A more practical derivation focuses on ensuring enough grain is present to yield the target batch size when mixed with the appropriate amount of water. The total volume of the mash is the water used plus the volume occupied by the grain. The amount of water *available* for wort is the total water minus what the grain absorbs.
Let's consider the total volume of the mash. Mash Thickness (T) is typically expressed as Volume of Water / Weight of Grain. So, Water = T * Grain Weight.
The final wort volume (Batch Size, B) comes from the total mash water (W) minus the water absorbed by the grain (G * A).
So, B ≈ W - (G * A)
Substitute W with T * G:
B ≈ (T * G) - (G * A)B ≈ G * (T - A)
Rearranging to solve for G (Grain Weight):
G = B / (T - A)
This formula tells us that the grain weight is the desired batch size divided by the difference between the mash thickness (water-to-grain ratio) and the grain's water absorption. This difference represents the effective volume of mash liquor contributing to the final wort.
Variables Table
Variable
Meaning
Unit
Typical Range
B (Batch Size)
Final volume of beer intended
Gallons or Liters
1 to 50+
T (Mash Thickness)
Ratio of mash water to grain
Quart/lb or L/kg
1.0 – 2.0 (common), up to 3.0
A (Grain Absorption)
Volume of water absorbed per unit weight of grain
Gallons/lb or L/kg
0.10 – 0.15 (common)
G (Grain Weight)
Total weight of grain required
Pounds or Kilograms
Calculated
W (Water for Mash)
Total volume of water used in the mash
Gallons or Liters
Calculated
Water Lost
Volume of water retained by grain
Gallons or Liters
Calculated
Practical Examples (Real-World Use Cases)
Example 1: Standard 5-Gallon IPA Batch
A homebrewer wants to make a 5-gallon IPA. They prefer a fairly standard mash thickness of 1.3 quarts per pound and know their grains typically absorb about 0.125 gallons per pound.
Total Grain Weight = Batch Size / Effective Mash Ratio = 5 gallons / 0.200 gal/lb = 25 lbs
Water Needed = Total Grain Weight * Mash Thickness = 25 lbs * 1.3 qt/lb = 32.5 quarts
*Conversion: 32.5 quarts ≈ 8.13 gallons*
Water Lost to Grain = Total Grain Weight * Grain Absorption = 25 lbs * 0.125 gal/lb = 3.125 gallons
Result Interpretation: The brewer needs approximately 25 pounds of grain for their 5-gallon batch. They will need about 8.13 gallons of water for the mash itself. Of this water, roughly 3.125 gallons will be retained by the grain, leaving about 5.005 gallons of wort, which matches the target batch size. This quantity of grain should fit comfortably within a standard 5-gallon mash tun.
Example 2: High-Gravity Stout (10 Liter Batch)
A brewer is planning a 10-liter high-gravity stout. They are using a thicker mash of 2.5 L/kg to maximize extract and their grains absorb approximately 0.26 L/kg.
Total Grain Weight = Batch Size / Effective Mash Ratio = 10 Liters / 2.24 L/kg ≈ 4.46 kg
Water Needed = Total Grain Weight * Mash Thickness = 4.46 kg * 2.5 L/kg ≈ 11.15 Liters
Water Lost to Grain = Total Grain Weight * Grain Absorption = 4.46 kg * 0.26 L/kg ≈ 1.16 Liters
Result Interpretation: For a 10-liter high-gravity stout, the brewer requires approximately 4.46 kilograms of grain. This will necessitate about 11.15 liters of water for the mash. Around 1.16 liters of this water will be absorbed by the grain, yielding the target 10 liters of wort. This indicates a fairly concentrated mash, suitable for a high-gravity beer.
How to Use This Mash Tun Weight Calculator
Using the Mash Tun Weight Calculator is straightforward and designed to give you quick, accurate results for your brewing needs. Follow these simple steps:
Enter Desired Batch Size: Input the final volume of finished beer you intend to produce. This is typically measured in gallons (US) or liters.
Specify Mash Thickness: Enter your desired mash thickness. This is usually expressed in quarts per pound (qt/lb) or liters per kilogram (L/kg). Common values range from 1.0 to 2.0 qt/lb (2.1 to 4.2 L/kg). A lower number means a thicker mash.
Input Grain Water Absorption: Provide the estimated amount of water your grain will absorb. This is usually around 0.125 gallons per pound (0.26 L/kg) for typical malted grains.
Click "Calculate Grain Weight": Once all values are entered, click the button. The calculator will instantly update with your results.
Understanding the Results
The calculator provides the following key outputs:
Total Grain Weight (Main Result): This is the primary number – the total weight of grain (in pounds or kilograms) you need for your mash.
Total Mash Volume: The total volume of water you should use for your mash.
Water Needed for Mash: A more direct display of the calculated mash water volume.
Water Lost to Grain: An estimate of how much water will be absorbed by the grain and retained, which is crucial for calculating boil-off rates and sparge volumes.
Formula Explanation: A brief description of the mathematical basis for the calculation.
Use the "Copy Results" button to easily transfer these figures for your brewing logs or recipe documentation.
Decision-Making Guidance
The calculated grain weight is a primary input for your brew day.
Mash Tun Fit: Ensure the calculated total grain weight, along with the calculated water volume, will physically fit into your mash tun. Overfilling can cause issues with temperature control and grain bed compaction.
Recipe Scaling: If you are scaling a recipe up or down, recalculating the grain weight is essential.
Efficiency Adjustments: If you consistently achieve higher or lower brewhouse efficiency than planned, you might adjust your grain bill slightly in future brews, but start with the calculated amount.
Key Factors That Affect Mash Tun Weight Results
While the core calculation is straightforward, several factors can influence the *actual* grain weight needed and how brewers interpret the results. Understanding these nuances helps refine brewing processes.
Grain Type and Profile: Different grains have slightly different densities and absorption rates. While the calculator uses a general absorption rate, highly flaked grains or specialty malts might behave differently. Adjusting the absorption input based on your specific grain bill can improve accuracy.
Mash Thickness Preference: Brewers choose mash thickness based on desired wort characteristics. Thicker mashes (lower qt/lb) tend to favor beta-amylase activity (producing more fermentable sugars), while thinner mashes (higher qt/lb) favor alpha-amylase (producing more body). Your choice directly impacts the water-to-grain ratio.
Water pH and Mineral Content: While not directly in the grain weight formula, water chemistry affects enzyme activity and mash efficiency. Brewers often adjust mash water pH, which can indirectly influence how enzymes function and thus the overall sugar extraction. Higher efficiency means you might need slightly less grain for the same target gravity.
Temperature Control Accuracy: Precise temperature control during the mash is vital. If your mash temperature deviates significantly from the target, enzyme activity can be suboptimal, potentially lowering the amount of sugar extracted. This could mean your calculated grain weight might yield a slightly lower gravity beer than intended if efficiency drops.
Grain Milling: The fineness of the grain crush significantly impacts the surface area available for enzymatic conversion and water penetration. An overly coarse crush can lead to poor efficiency, while a crush that is too fine can lead to lautering problems. For this calculation, we assume an optimal crush.
Brewing System Variations: Different mash tun designs, False Bottom vs. Bazooka Screen setups, and stirring techniques can slightly affect water flow and grain bed uniformity, potentially influencing achievable extraction efficiency.
Target Gravity vs. Batch Size: This calculator focuses on achieving a target *volume*. If your goal is a specific Original Gravity (OG) for a given batch size, the grain weight calculation is the first step. However, achieving that OG depends heavily on your system's brewhouse efficiency. If your efficiency is lower than assumed, you'd need more grain to hit the target OG.
Boil-Off Rate and Shrinkage: The calculation focuses on the mash stage. Remember to factor in your system's boil-off rate (water evaporating during the boil) and potential wort shrinkage/expansion when planning your final volumes and grain bill. The calculator's output is the *initial* grain needed.
Frequently Asked Questions (FAQ)
What is the standard mash thickness for most beers?
A common and versatile mash thickness for many beer styles is between 1.25 to 1.5 quarts per pound (approximately 2.6 to 3.1 L/kg). This range generally provides good enzyme activity for efficient sugar conversion while maintaining a manageable mash consistency. However, specific styles might benefit from thicker (e.g., high-gravity stouts) or thinner mashes.
How much water does grain actually absorb?
Malted grains typically absorb around 0.10 to 0.15 gallons of water per pound (about 0.21 to 0.31 L/kg). The calculator defaults to 0.125 gal/lb (0.26 L/kg), which is a good average. This absorption value can vary slightly based on the grain type, the degree of milling, and the pH of the mash water.
Can I use this calculator for both US gallons and Liters?
Yes, the calculator is designed to work with either unit system. Ensure you are consistent: if you input the batch size in gallons, use mash thickness in quarts/pound and absorption in gallons/pound. If you use liters for batch size, use L/kg for both mash thickness and absorption. The units for the results (grain weight, water volumes) will correspond to the units used for input.
What happens if I use too much or too little grain?
Using too little grain for your target batch size and gravity can result in lower efficiency, meaning you won't extract enough sugars. This leads to a beer with lower alcohol content and less body. Using too much grain might exceed your mash tun's capacity, lead to a stuck sparge (poor runoff), or result in unnecessarily high gravity wort that is difficult to ferment completely.
Does the type of grain matter for absorption?
Yes, slightly. Base malts like Pale Malt or Pilsner Malt have fairly standard absorption rates. Flaked grains (flaked barley, flaked oats) can sometimes absorb slightly more water. Specialty malts might vary minimally. For most homebrewers, using the default 0.125 gal/lb (0.26 L/kg) is sufficient, but advanced brewers may fine-tune this value based on their specific grain bill composition.
How does mash tun size relate to the calculated grain weight?
The calculated grain weight, along with the calculated mash water volume, determines the total volume of your mash. You must ensure your mash tun has sufficient capacity to hold this total volume without overflowing. A general rule of thumb is that the mash tun should have a capacity at least 1.5 to 2 times the volume of your grain bill alone.
What if my brewhouse efficiency is different from average?
This calculator primarily focuses on the physical mash requirements (grain and water volumes). Brewhouse efficiency is a measure of how effectively your *entire system* converts grain into fermentable sugars. If your efficiency is consistently lower than the assumed average (often around 70-75%), you might need to slightly increase your grain bill to reach your target Original Gravity. Conversely, higher efficiency might allow for a slight reduction.
Should I adjust my grain weight based on yeast health?
Yeast health is critical for fermentation, but it doesn't directly alter the *required* grain weight calculation for the mash itself. However, if you anticipate a difficult fermentation due to less-than-ideal yeast health or a very high-gravity wort, you might choose to slightly reduce the grain bill to lower the initial sugar concentration, making it easier for the yeast to handle. Always ensure proper yeast pitching rates and aeration.
Related Tools and Internal Resources
Mash Tun Calculator: Our primary tool for calculating grain and water needs.
Brew Day Planner: A comprehensive checklist and guide to help you prepare for and execute your brewing day smoothly.
Strike Water Calculator: Essential for determining the correct temperature and volume of water to add to your grain for mashing.
Boil-Off Calculator: Helps estimate how much water you'll lose during the boiling process, crucial for achieving your target batch volume.
Fermentation Temperature Guide: Learn about the ideal temperature ranges for different yeast strains to ensure optimal flavor development.
Water Chemistry Primer: Understand how adjusting your brewing water can impact the flavor and characteristics of your beer.
Visualizing Mash Tun Grain Weight Data
The chart below illustrates how changes in mash thickness and grain absorption affect the total mash volume required for a consistent batch size. Understanding this relationship helps in planning and resource allocation.
Mash Tun Calculation Parameters and Outputs
Parameter/Output
Unit
Example 1 Value
Example 2 Value
Desired Batch Size
Gallons / Liters
5 / —
— / 10
Mash Thickness
qt/lb or L/kg
1.3
2.5
Grain Absorption
gal/lb or L/kg
0.125
0.26
Total Grain Weight
Pounds / Kilograms
25 / —
— / 4.46
Total Mash Volume
Quarts / Liters
32.5 / — (≈ 8.13 gal)
— / 11.15
Water Lost to Grain
Gallons / Liters
3.125 / —
— / 1.16
// Chart Configuration
var ctx = document.getElementById('mashTunChart').getContext('2d');
var mashTunChart; // Declare chart variable
// Default values for chart rendering on load
var defaultBatchSize = 5;
var defaultMashThickness = 1.3;
var defaultGrainAbsorption = 0.125;
function createOrUpdateChart(batchSize, mashThickness, grainAbsorption) {
var dataPoints = [];
var mashThicknessValues = [1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0]; // Range for Mash Thickness
var absorptionValues = [0.10, 0.11, 0.12, 0.13, 0.14, 0.15]; // Range for Grain Absorption
var simulatedMashThickness = mashThickness; // Use the current input value
var simulatedGrainAbsorption = grainAbsorption; // Use the current input value
// Generate data for Mash Thickness variation
for (var i = 0; i < dataPoints.length; i++) {
dataPoints[i].mashThickness = [];
dataPoints[i].totalMashVolume = [];
dataPoints[i].waterLostToGrain = [];
}
var mashThicknessSeries = [];
var totalMashVolumeSeries = [];
var waterLostToGrainSeries = [];
for (var i = 0; i L/kg) – Correction: Using direct qt/lb and gal/lb relationship. 1 qt = 0.25 gal. So T in gal/lb = T_qt/lb * 0.25.
// Let's correct the formula interpretation: Mash Thickness T is typically given as Vol Water / Weight Grain.
// If T is in qt/lb, and A is in gal/lb:
// Water (qt) = T_qt/lb * G
// Water (gal) = T_qt/lb * 0.25 * G
// Water Lost (gal) = A_gal/lb * G
// Batch Size (gal) = Water (gal) – Water Lost (gal) = (T_qt/lb * 0.25 * G) – (A_gal/lb * G)
// Batch Size (gal) = G * (T_qt/lb * 0.25 – A_gal/lb)
// G = Batch Size / (T_qt/lb * 0.25 – A_gal/lb)
// Total Mash Volume (gal) = G * (T_qt/lb * 0.25)
// Assuming the input "mashThickness" is directly in gal/lb for calculation ease OR the user inputs consistent units (e.g. 1.3 qt/lb is interpreted relative to the batch size unit)
// The formula G = B / (T – A) derived earlier uses T and A in *consistent* units (e.g., both gal/lb).
// Let's assume T is in gal/lb for the chart calculation for simplicity here, or requires conversion if qt/lb is input.
// Given the example used 1.3 qt/lb and 0.125 gal/lb, the formula G = B / (T-A) works if T is converted to gal/lb.
// 1.3 qt/lb = 0.325 gal/lb. So, T = 0.325. A = 0.125. T-A = 0.2.
// If B=5 gal, G = 5 / 0.2 = 25 lbs. Total Mash Volume = G * T = 25 * 0.325 = 8.125 gal.
// Water Lost = G * A = 25 * 0.125 = 3.125 gal.
var currentMashThicknessGalPerLb = currentMashThickness * 0.25; // Convert qt/lb to gal/lb for consistency IF input is qt/lb
// HOWEVER, the examples imply T is directly usable IF units are consistent. Let's stick to the G = B / (T – A) logic and assume T, A, B are in compatible units.
// For the chart, let's use the direct interpretation of T (qt/lb) and A (gal/lb) assuming B is in gal.
// We need to convert T (qt/lb) to gal/lb for subtraction with A (gal/lb).
var T_gal_per_lb = currentMashThickness * 0.25; // Convert qt/lb to gal/lb
if (T_gal_per_lb > simulatedGrainAbsorption) { // Ensure valid calculation
var calculatedGrainWeight = batchSize / (T_gal_per_lb – simulatedGrainAbsorption);
var calculatedMashVolume = calculatedGrainWeight * currentMashThickness * 0.25; // Result in gallons
var calculatedWaterLost = calculatedGrainWeight * simulatedGrainAbsorption;
mashThicknessSeries.push({ x: currentMashThickness, y: calculatedGrainWeight }); // x-axis: Mash Thickness, y-axis: Grain Weight
totalMashVolumeSeries.push({ x: currentMashThickness, y: calculatedMashVolume });
waterLostToGrainSeries.push({ x: currentMashThickness, y: calculatedWaterLost });
}
}
var absorptionSeries = [];
var grainWeightForAbsorptionSeries = [];
var waterLostForAbsorptionSeries = [];
for (var i = 0; i currentAbsorption) { // Ensure valid calculation
var calculatedGrainWeight = batchSize / (T_gal_per_lb_fixed – currentAbsorption);
var calculatedMashVolume = calculatedGrainWeight * T_gal_per_lb_fixed; // Mash Volume (gal) = G * T (gal/lb)
var calculatedWaterLost = calculatedGrainWeight * currentAbsorption;
absorptionSeries.push({ x: currentAbsorption, y: calculatedGrainWeight }); // x-axis: Grain Absorption, y-axis: Grain Weight
grainWeightForAbsorptionSeries.push({ x: currentAbsorption, y: calculatedMashVolume });
waterLostForAbsorptionSeries.push({ x: currentAbsorption, y: calculatedWaterLost });
}
}
// Destroy previous chart instance if it exists
if (mashTunChart) {
mashTunChart.destroy();
}
// Create new chart
mashTunChart = new Chart(ctx, {
type: 'line',
data: {
datasets: [
{
label: 'Grain Weight vs. Mash Thickness (fixed absorption)',
data: mashThicknessSeries,
borderColor: 'rgba(0, 74, 153, 1)', // Primary color
backgroundColor: 'rgba(0, 74, 153, 0.2)',
fill: false,
tension: 0.1,
pointRadius: 4,
pointHoverRadius: 6
},
{
label: 'Total Mash Volume vs. Mash Thickness (fixed absorption)',
data: totalMashVolumeSeries,
borderColor: 'rgba(40, 167, 69, 1)', // Success color
backgroundColor: 'rgba(40, 167, 69, 0.2)',
fill: false,
tension: 0.1,
pointRadius: 4,
pointHoverRadius: 6,
hidden: true // Initially hidden, can be toggled
},
{
label: 'Water Lost vs. Mash Thickness (fixed absorption)',
data: waterLostToGrainSeries,
borderColor: 'rgba(23, 162, 184, 1)', // Info color
backgroundColor: 'rgba(23, 162, 184, 0.2)',
fill: false,
tension: 0.1,
pointRadius: 4,
pointHoverRadius: 6,
hidden: true // Initially hidden
}
]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: 'Mash Thickness (qt/lb)',
color: 'var(–primary-color)'
},
ticks: {
beginAtZero: false,
callback: function(value) {
return value.toFixed(1);
}
}
},
y: {
title: {
display: true,
text: 'Weight (lbs) / Volume (gal)',
color: 'var(–primary-color)'
},
ticks: {
beginAtZero: true,
callback: function(value) {
// Simple check if it's likely a weight or volume based on typical values
if (value > 100) return value.toFixed(1) + ' gal'; // Assume large values are volumes
return value.toFixed(1) + ' lbs'; // Assume smaller values are weights
}
}
}
},
plugins: {
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
label += context.parsed.y.toFixed(2);
// Add unit based on series type
if (context.dataset.label.includes('Weight')) {
label += ' lbs';
} else if (context.dataset.label.includes('Volume')) {
label += ' gal';
} else if (context.dataset.label.includes('Lost')) {
label += ' gal';
}
return label;
}
}
},
legend: {
position: 'top',
}
}
}
});
}
// Function to toggle FAQ content
function toggleFaq(element) {
var content = element.nextElementSibling;
element.classList.toggle('active');
if (content.style.display === "block") {
content.style.display = "none";
} else {
content.style.display = "block";
}
}
// Helper function to validate input
function validateInput(id, errorId, minValue, maxValue) {
var input = document.getElementById(id);
var errorElement = document.getElementById(errorId);
var value = parseFloat(input.value);
var isValid = true;
errorElement.classList.remove('visible');
input.style.borderColor = 'var(–border-color)';
if (isNaN(value)) {
errorElement.textContent = "Please enter a valid number.";
errorElement.classList.add('visible');
input.style.borderColor = '#dc3545';
isValid = false;
} else if (value maxValue) {
errorElement.textContent = "Value is too high. Please check your input.";
errorElement.classList.add('visible');
input.style.borderColor = '#dc3545';
isValid = false;
}
return isValid;
}
// Main calculation function
function calculateMashTunWeight() {
var batchSize = parseFloat(document.getElementById('batchSize').value);
var mashThickness = parseFloat(document.getElementById('mashThickness').value);
var grainAbsorption = parseFloat(document.getElementById('grainAbsorption').value);
var isValid = true;
// Validate inputs
if (!validateInput('batchSize', 'batchSizeError', 0.1)) isValid = false;
if (!validateInput('mashThickness', 'mashThicknessError', 0.1, 5.0)) isValid = false; // Max thickness reasonable
if (!validateInput('grainAbsorption', 'grainAbsorptionError', 0.01, 0.5)) isValid = false; // Max absorption reasonable
if (!isValid) {
// Clear results if validation fails
document.getElementById('totalGrainWeight').textContent = '–';
document.getElementById('totalMashVolume').textContent = '–';
document.getElementById('waterForMash').textContent = '–';
document.getElementById('waterLostToGrain').textContent = '–';
return;
}
// Unit handling: Assuming consistent units are used (e.g., gal, qt/lb, gal/lb OR L, L/kg, L/kg)
// The core formula G = B / (T – A) requires T and A to be in compatible units relative to B.
// Let's assume the user is using US customary units (gallons for Batch Size, qt/lb for Mash Thickness, gal/lb for Absorption)
// If user inputs qt/lb for Mash Thickness, we need to convert it to gal/lb to subtract A (which is in gal/lb)
var mashThicknessGalPerLb = mashThickness * 0.25; // Convert qt/lb to gal/lb
if (mashThicknessGalPerLb <= grainAbsorption) {
document.getElementById('mashThicknessError').textContent = "Mash thickness must be greater than grain absorption.";
document.getElementById('mashThicknessError').classList.add('visible');
document.getElementById('totalGrainWeight').textContent = 'Error';
document.getElementById('totalMashVolume').textContent = 'Error';
document.getElementById('waterForMash').textContent = 'Error';
document.getElementById('waterLostToGrain').textContent = 'Error';
return;
}
var totalGrainWeight = batchSize / (mashThicknessGalPerLb – grainAbsorption);
var waterForMashGal = totalGrainWeight * mashThicknessGalPerLb; // Total mash volume in gallons
var waterLostToGrainGal = totalGrainWeight * grainAbsorption;
// Format results to 2 decimal places
document.getElementById('totalGrainWeight').textContent = totalGrainWeight.toFixed(2);
document.getElementById('totalMashVolume').textContent = waterForMashGal.toFixed(2);
document.getElementById('waterForMash').textContent = waterForMashGal.toFixed(2); // Renamed for clarity
document.getElementById('waterLostToGrain').textContent = waterLostToGrainGal.toFixed(2);
// Update chart with current values for better context
createOrUpdateChart(batchSize, mashThickness, grainAbsorption);
}
// Function to reset form to default values
function resetForm() {
document.getElementById('batchSize').value = '5';
document.getElementById('mashThickness').value = '1.3';
document.getElementById('grainAbsorption').value = '0.125';
// Clear errors
document.getElementById('batchSizeError').textContent = '';
document.getElementById('batchSizeError').classList.remove('visible');
document.getElementById('mashThicknessError').textContent = '';
document.getElementById('mashThicknessError').classList.remove('visible');
document.getElementById('grainAbsorptionError').textContent = '';
document.getElementById('grainAbsorptionError').classList.remove('visible');
// Reset input borders
document.getElementById('batchSize').style.borderColor = 'var(–border-color)';
document.getElementById('mashThickness').style.borderColor = 'var(–border-color)';
document.getElementById('grainAbsorption').style.borderColor = 'var(–border-color)';
// Recalculate with default values
calculateMashTunWeight();
}
// Function to copy results to clipboard
function copyResults() {
var mainResult = document.getElementById('totalGrainWeight').textContent;
var intermediateValues = {
totalMashVolume: document.getElementById('totalMashVolume').textContent,
waterForMash: document.getElementById('waterForMash').textContent,
waterLostToGrain: document.getElementById('waterLostToGrain').textContent
};
var assumptions = {
batchSize: document.getElementById('batchSize').value,
mashThickness: document.getElementById('mashThickness').value + " qt/lb", // Append typical units
grainAbsorption: document.getElementById('grainAbsorption').value + " gal/lb" // Append typical units
};
var resultText = "Mash Tun Grain Weight Calculation:\n\n";
resultText += "Primary Result:\n";
resultText += "Total Grain Weight Required: " + mainResult + " lbs\n\n"; // Assuming lbs output
resultText += "Key Intermediate Values:\n";
resultText += "Total Mash Volume: " + intermediateValues.totalMashVolume + " gal\n";
resultText += "Water for Mash: " + intermediateValues.waterForMash + " gal\n";
resultText += "Water Lost to Grain: " + intermediateValues.waterLostToGrain + " gal\n\n";
resultText += "Key Assumptions:\n";
resultText += "Desired Batch Size: " + assumptions.batchSize + " gal\n";
resultText += "Mash Thickness: " + assumptions.mashThickness + "\n";
resultText += "Grain Water Absorption: " + assumptions.grainAbsorption + "\n";
// Use Clipboard API if available, fallback to prompt
if (navigator.clipboard && navigator.clipboard.writeText) {
navigator.clipboard.writeText(resultText).then(function() {
alert('Results copied to clipboard!');
}).catch(function(err) {
console.error('Could not copy text: ', err);
prompt('Copy this text:', resultText);
});
} else {
prompt('Copy this text:', resultText);
}
}
// Initial calculation on page load
document.addEventListener('DOMContentLoaded', function() {
// Ensure chart canvas exists before trying to initialize
if (document.getElementById('mashTunChart')) {
createOrUpdateChart(defaultBatchSize, defaultMashThickness, defaultGrainAbsorption);
}
calculateMashTunWeight(); // Perform initial calculation
});