✦ SOLVORY FREE TOOLS · HOME & DIY
Paint Coverage Calculator — Free Online Tool
Estimate interior paint quantities by wall size, identical wall count, openings, coat coverage and waste allowance.
JavaScript is needed for the interactive tool. The formula and worked example remain available below.
How to use the Paint Coverage Calculator
Estimate interior paint quantities by wall size, identical wall count, openings, coat coverage and waste allowance.
- Enter real measurements or prices in the interactive tool.
- Check unit labels and customize any applicable fees, waste allowances or product-specific rates.
- Review the result, formulas and limitations before using it in purchasing, pricing or production decisions.
Paint Coverage Calculator: formula & methodology
Net square feet = total wall length × height × number of walls − window/door area. Gallons = net surface × coats × waste factor ÷ paint coverage per gallon.
The tool uses your entered values and explicitly labeled assumptions. Final results may be rounded for display, while intermediate arithmetic retains available numeric precision. Verify material, tax, device or platform specifications relevant to your situation.
Worked example
A 100 sq ft wall with two coats and 100 sq ft coverage per gallon requires 2 US gallons before additional waste.
Try the example above and then change values to reflect your own project or comparison.
Frequently asked questions
Does it include windows?
Yes, subtract the combined opening area you enter. Always check product coverage and surface porosity.
How do I use the coverage rate on my paint tin?
Enter the manufacturer’s stated square feet covered by one US gallon for a single coat. Reduce that value if the surface is rough or absorbent.
Can I enter wall dimensions in meters?
Yes. Wall length and height can be in meters, but openings and product coverage remain labeled in square feet.