Estimating the right amount of paint is crucial for any home improvement project. Overbuying leads to waste, while underbuying means inconvenient trips back to the store. This Benjamin Moore Paint Calculator helps you determine your needs based on the dimensions of your walls, the number of coats you plan to apply, and the specific coverage of the paint you choose.
How it Works:
The calculator uses a straightforward formula to estimate the total square footage you need to paint and then divides it by the paint's coverage rate.
Total Wall Area: We sum the square footage of all the walls you intend to paint.
Subtract Non-Painted Areas: Doors and windows do not need to be painted, so their areas are subtracted from the total wall area.
Account for Coats: The total paintable area is multiplied by the number of coats you will apply. For example, painting a wall twice doubles the required paint.
Calculate Gallons Needed: The final adjusted square footage is then divided by the paint's coverage rate (typically listed on the paint can, and Benjamin Moore paints often cover around 400 sq ft per gallon).
The Formula:
Gallons Needed = ((Wall Area 1 + Wall Area 2 + Wall Area 3 + Wall Area 4) - Door Area - Window Area) * Number of Coats / Coverage per Gallon
Example:
Let's say you have a room with four walls and need to paint them.
Wall 1: 120 sq ft
Wall 2: 150 sq ft
Wall 3: 135 sq ft
Wall 4: 160 sq ft
Door Area: 20 sq ft
Window Area: 30 sq ft
Number of Coats: 2
Coverage per Gallon (Benjamin Moore Aura): 400 sq ft/gallon
Calculation:
Total Wall Area = 120 + 150 + 135 + 160 = 565 sq ft
Paintable Area = 565 sq ft – 20 sq ft – 30 sq ft = 515 sq ft
Total Area to Cover (with 2 coats) = 515 sq ft * 2 = 1030 sq ft
In this scenario, you would likely want to purchase 3 gallons to ensure you have enough, especially if accounting for touch-ups or slight variations in surface texture.
Tips for Accurate Measurement:
Measure the length and height of each wall and multiply them to get the square footage.
Measure doors and windows accurately and subtract their total area.
If you have complex architectural features (e.g., vaulted ceilings, many windows), it's better to slightly overestimate than underestimate.
Always check the specific coverage information on the Benjamin Moore paint can you choose, as different finishes and formulations can vary slightly.
function calculatePaint() {
var wallArea1 = parseFloat(document.getElementById("wallArea1").value);
var wallArea2 = parseFloat(document.getElementById("wallArea2").value);
var wallArea3 = parseFloat(document.getElementById("wallArea3").value);
var wallArea4 = parseFloat(document.getElementById("wallArea4").value);
var doorArea = parseFloat(document.getElementById("doorArea").value);
var windowArea = parseFloat(document.getElementById("windowArea").value);
var coats = parseInt(document.getElementById("coats").value);
var coveragePerGallon = parseFloat(document.getElementById("coveragePerGallon").value);
var resultValueElement = document.getElementById("result-value");
var resultUnitElement = document.getElementById("result-unit");
// Validate inputs
if (isNaN(wallArea1) || isNaN(wallArea2) || isNaN(wallArea3) || isNaN(wallArea4) ||
isNaN(doorArea) || isNaN(windowArea) || isNaN(coats) || isNaN(coveragePerGallon)) {
resultValueElement.innerText = "Invalid";
resultUnitElement.innerText = "Please enter valid numbers.";
return;
}
if (coveragePerGallon <= 0) {
resultValueElement.innerText = "Error";
resultUnitElement.innerText = "Coverage must be greater than zero.";
return;
}
var totalWallArea = wallArea1 + wallArea2 + wallArea3 + wallArea4;
var paintableArea = totalWallArea – doorArea – windowArea;
// Ensure paintable area is not negative
if (paintableArea 0
var finalGallons = Math.ceil(gallonsNeeded);
if (gallonsNeeded > 0 && finalGallons === 0) {
finalGallons = 1; // Ensure at least 1 gallon is recommended if calculation results in a fraction close to zero
} else if (gallonsNeeded === 0) {
finalGallons = 0; // If input areas result in 0 paint needed
}
resultValueElement.innerText = finalGallons;
resultUnitElement.innerText = "Gallons";
}