How the paint calculator works
The calculator starts with the perimeter of a rectangular room, multiplies by wall height, subtracts doors and windows, then multiplies by the number of coats. The remaining paintable area is divided by the coverage rate printed on your paint product.
Example
A 12 × 10 ft room with 8 ft walls has 352 ft² of gross wall area before subtracting openings. Two coats require roughly twice the single-coat coverage.
Use the label: actual coverage varies with surface texture, primer, application method, color change, and product formulation. Replace the default coverage rate with the manufacturer’s number when available.
Paint calculator FAQ
Should doors and windows be subtracted?
Yes, if you want a tighter estimate. Enter the combined opening area.
Does a second coat double the paint?
In the basic area calculation, yes. Real-world touchups and surface absorption can change the final amount.
Should I round up?
Paint is purchased in fixed container sizes, so round to a practical purchase quantity and keep some material for touchups when appropriate.