Flow Rate Calculator Time Volume

Flow Rate Calculator

Calculate Flow Rate, Volume, or Time using the Q = V/t formula.

Flow Rate (Q) Volume (V) Time (t)

e.g., Liters, Gallons, m³

e.g., Seconds, Minutes, Hours

Result:

Whether you are an engineer designing a piping system, a pool owner estimating filling time, or a medical professional setting up an IV drip, understanding the relationship between Flow Rate, Volume, and Time is essential. This calculator helps you solve for any of these three variables instantly.

The Flow Rate Formula

The calculation is based on the fundamental physics equation for volumetric flow rate:

Q = V / t

Where:

• Q (Flow Rate): The amount of fluid that passes through a specific point over a specific period. Common units include Liters per minute (L/min), Gallons per minute (GPM), or Cubic meters per second (m³/s).
• V (Volume): The total quantity of fluid. Common units are Liters, Gallons, or Cubic meters.
• t (Time): The duration it takes for the fluid to flow. Common units are Seconds, Minutes, or Hours.

How to Use This Calculator

This tool is dynamic. Depending on what information you have, select the appropriate mode from the dropdown menu:

1. Calculating Flow Rate (Q)

Select this mode if you know the total volume of liquid and how long it took to move it.

• Scenario: You filled a 5-gallon bucket in exactly 2 minutes.
• Input: Volume = 5, Time = 2.
• Result: 2.5 Gallons per Minute.

2. Calculating Volume (V)

Select this mode if you know the flow rate of your equipment and the duration it has been running.

• Formula: V = Q × t
• Scenario: A pump runs at 50 Liters/minute for 30 minutes.
• Input: Flow Rate = 50, Time = 30.
• Result: 1,500 Liters total volume.

3. Calculating Time (t)

Select this mode to find out how long a task will take given a specific volume and flow speed.

• Formula: t = V / Q
• Scenario: You need to empty a 10,000-gallon pool with a pump rated at 500 GPM.
• Input: Volume = 10,000, Flow Rate = 500.
• Result: 20 Minutes to empty.

Common Applications

• Plumbing: Calculating water pressure and pipe sizing requirements.
• Pool Maintenance: Estimating fill times or turnover rates for filtration systems.
• Medical: IV infusion calculations (drops per minute or mL per hour).
• Industrial: Managing chemical dosing or wastewater treatment processes.

Note on Units

This calculator works with pure numbers. Ensure you keep your units consistent! If you enter Volume in Gallons and Time in Minutes, your Flow Rate result will be in Gallons per Minute.

// Update input labels based on dropdown selection function updateFlowForm() { var mode = document.getElementById('solveFor').value; var label1 = document.getElementById('label1'); var label2 = document.getElementById('label2'); var hint1 = document.getElementById('unitHint1'); var hint2 = document.getElementById('unitHint2'); var resultDiv = document.getElementById('flowResult'); // Hide previous result when changing modes resultDiv.style.display = 'none'; document.getElementById('input1').value = "; document.getElementById('input2').value = "; if (mode === 'rate') { label1.innerText = "Total Volume (V)"; hint1.innerText = "e.g., Liters, Gallons, m³"; label2.innerText = "Total Time (t)"; hint2.innerText = "e.g., Seconds, Minutes, Hours"; } else if (mode === 'volume') { label1.innerText = "Flow Rate (Q)"; hint1.innerText = "e.g., L/min, GPM, m³/s"; label2.innerText = "Total Time (t)"; hint2.innerText = "e.g., Seconds, Minutes, Hours"; } else if (mode === 'time') { label1.innerText = "Total Volume (V)"; hint1.innerText = "e.g., Liters, Gallons, m³"; label2.innerText = "Flow Rate (Q)"; hint2.innerText = "e.g., L/min, GPM, m³/s"; } } // Perform the Calculation function calculateFlow() { var mode = document.getElementById('solveFor').value; var val1 = parseFloat(document.getElementById('input1').value); var val2 = parseFloat(document.getElementById('input2').value); var resultElement = document.getElementById('resultValue'); var explanationElement = document.getElementById('resultExplanation'); var resultDiv = document.getElementById('flowResult'); // Validation: Check if inputs are numbers if (isNaN(val1) || isNaN(val2)) { alert("Please enter valid numbers for both fields."); return; } var result = 0; var resultText = ""; var explanationText = ""; if (mode === 'rate') { // Formula: Rate = Volume / Time if (val2 === 0) { alert("Time cannot be zero."); return; } result = val1 / val2; // Formatting result resultText = result % 1 === 0 ? result : result.toFixed(4); resultText += " (Units of Volume / Units of Time)"; explanationText = "Calculation: " + val1 + " (Vol) / " + val2 + " (Time) = " + resultText; } else if (mode === 'volume') { // Formula: Volume = Rate * Time result = val1 * val2; resultText = result % 1 === 0 ? result : result.toFixed(4); resultText += " (Units of Volume)"; explanationText = "Calculation: " + val1 + " (Rate) × " + val2 + " (Time) = " + resultText; } else if (mode === 'time') { // Formula: Time = Volume / Rate if (val2 === 0) { alert("Flow Rate cannot be zero."); return; } result = val1 / val2; resultText = result % 1 === 0 ? result : result.toFixed(4); resultText += " (Units of Time)"; explanationText = "Calculation: " + val1 + " (Vol) / " + val2 + " (Rate) = " + resultText; } // Display Result resultElement.innerText = resultText; explanationElement.innerText = explanationText; resultDiv.style.display = 'block'; } // Initialize form labels on load window.onload = function() { updateFlowForm(); };