Paint Calculator

Estimate paint from room walls, openings, coats, and manufacturer coverage. Use the explicitly labelled inputs below; rates, dimensions, and costs are assumptions, not live quotes.

Enter your values in the calculator fields to get an instant result.

Calculator guide

Estimate paint from room walls, openings, coats, and manufacturer coverage. Use the explicitly labelled inputs below; rates, dimensions, and costs are assumptions, not live quotes.

Formula or method

Wall area = 2 × (room length + width) × wall height − openings. Gallons = ceiling(wall area × coats × (1 + allowance/100) ÷ coverage per gallon).

How to use this calculator

  1. Set Room length (ft). The interface starts with 16; replace it with the value for your scenario.
  2. Set Room width (ft). The interface starts with 12; replace it with the value for your scenario.
  3. Set Wall height (ft). The interface starts with 8; replace it with the value for your scenario.
  4. Set Doors and windows (sq ft). The interface starts with 40; replace it with the value for your scenario.
  5. Set Coats. The interface starts with 2; replace it with the value for your scenario.
  6. Set Coverage per gallon (sq ft). The interface starts with 350; replace it with the value for your scenario.
  7. Set Extra paint (%). The interface starts with 10; replace it with the value for your scenario.
  8. Compare the result with the worked example, then vary one assumption at a time so you can see what changes.

Worked example

Enter Room length = 16 ft; Room width = 12 ft; Wall height = 8 ft; Doors and windows = 40 sq ft; Coats = 2; Coverage per gallon = 350 sq ft; Extra paint = 10 %. With those assumptions, the calculator gives Paintable wall area: 408 sq ft; Gallons to buy: 3 gal; Coverage including coats: 897.6 sq ft; Formula: wall area × coats ÷ coverage. These outputs are calculated from the same implementation as the interactive tool.

Understanding the result

In this example, Paintable wall area is 408 sq ft. Gallons to buy is 3 gal. Verify measurements, manufacturer coverage, packaging, local code, and site conditions. Quantity and budget estimates do not certify structural or electrical safety.

Limitations and assumptions

  • Verify measurements, manufacturer coverage, packaging, local code, and site conditions. Quantity and budget estimates do not certify structural or electrical safety.
  • The worked example demonstrates the stated assumptions, not a recommendation about your personal circumstances.

Frequently asked questions

Which inputs should I check first?

For Paint Calculator, check Room length, Room width, Wall height, Doors and windows, Coats, Coverage per gallon, Extra paint. Keep the displayed units and select options consistent; do not treat default values as recommendations.

Why might my result differ from another tool?

Compare the other tool's paint calculator method, input units, rounding and assumptions. A matching title does not guarantee that both tools answer the same question.

Does a linked reference certify this result?

No. A reference can explain a formula or provide background for Paint Calculator, but it does not endorse this website, validate personal inputs or establish professional suitability.

Sources

Educational and planning information only. Sources are attributed background or formula references, not endorsements. Verify consequential decisions with an appropriate qualified professional.