Free home project calculator

Free room paint calculator

The paint calculator estimates paint amount for interior room walls based on room dimensions, wall height, openings, number of coats, and coverage rate.

Open this calculator

When to use this calculator

  • Estimate room paint amount
  • Account for doors and windows
  • Compare one coat vs. two coats
  • Use label coverage when available

Tips for a better estimate

  • Coverage changes by product, surface texture, and color change.
  • Primer may be needed separately.
  • Rough or porous surfaces may use more paint.
  • Keep extra paint for touch-ups.
HomeCalc gives planning estimates only. Product labels, package sizes, coverage rates, supplier conversions, local code, and site conditions can change the final quantity you need.

Frequently asked questions

Should I subtract doors and windows?

Yes, if you want a closer estimate. HomeCalc includes an openings allowance field.

Does primer count as a coat?

Primer is usually planned separately unless your product instructions say otherwise.

Why does coverage vary?

Surface texture, color, product type, and application method all affect coverage.