Measure wall area, account for coats, and add a small allowance before you shop. This guide explains a simple way to prepare your measurements before using the calculator.
Start with a clear sketch
Write down the shape, the units, and any openings or sections that change the measurement. A quick sketch makes it easier to catch a missed corner and gives you something useful to compare with a supplier quote.
- 1.Measure the total wall area instead of guessing from floor size.
- 2.Subtract large openings only when they materially change the estimate.
- 3.Use the paint label's coverage figure for the final product choice.
Keep the result realistic
Coverage numbers are averages. Texture, pattern, moisture, cuts, and the skill of the installer can all change the final amount. Treat the result as a first pass, then check the manufacturer's coverage, local rules, and the conditions at the project site.
Try the tool
Paint Calculator
Estimate gallons of paint for walls, ceilings, and trim with a practical waste allowance.
Open calculatorCommon questions
Should I round up?
Usually, yes. A small allowance helps with uneven surfaces, cuts, and product packaging. Confirm the final quantity with the product label or a local supplier.
Are these exact construction quantities?
No. They are planning estimates based on the measurements you enter. Project conditions and local building requirements can change the final order.