Construction calculator
Paint Calculator
Estimate gallons of paint needed for interior walls.
About the paint calculator
The paint calculator estimates how many gallons of paint you need based on wall area, number of coats, and paint coverage rate.
How to use this calculator
- 1
Calculate wall area
Measure total wall area in square feet, subtracting doors and windows.
- 2
Choose number of coats
Most projects need 2 coats. Dark-to-light color changes may need 3.
- 3
Enter coverage rate
Standard paint covers ~350 sq ft/gallon. Check your paint can for exact coverage.
How the calculation works
Total paint needed = (area × coats) ÷ coverage. Round up to full gallons.
Example: 500 sq ft with 2 coats at 350 sq ft/gal needs 3 gallons.
Why use construction calculators?
Construction projects involve significant material costs. Overestimating wastes money; underestimating causes delays. These calculators use standard industry formulas to give you reliable estimates for concrete, lumber, drywall, paint, roofing, flooring, and more. Always add 5–15% waste allowance for cuts, mistakes, and irregularities.
How to get accurate results
Measure twice, calculate once. Use a tape measure for dimensions, and enter values in the units shown. For irregular shapes, break the area into rectangles and calculate each separately. When in doubt, round up — it's better to have a little extra material than to run short mid-project.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about paint calculator
How accurate is the paint calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.