Home & Construction category
Material, utility, and project planning calculators for home jobs.
Paint Calculator
Estimate paint for one room or a whole house. Measure by room dimensions or direct wall area, subtract doors and windows, include ceilings, and see gallons, quarts, and cost instantly.
Rooms
Add each room, switch between dimensions or direct wall area, and include ceilings if needed.
Subtracts 20 sq ft each.
Subtracts 15 sq ft each.
Total area
0.0 sq ft
Paintable area
0.0 sq ft
Openings removed
20.0 sq ft
Room
Room 1
Paint Estimate
Total wall area
0.0 sq ft
Paintable area
0.0 sq ft
Gallons needed
0.00 gal
Quarts needed
0.0 qt
Estimated paint cost
$0.00
Assumptions
2 coats at 350 sq ft per gallon.
EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.
Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.
Learn more about our review process on the EveryCalc methodology page.
Calculation notes and example
Paint area, coats, and coverage formula
For a rectangular room, gross wall area equals perimeter multiplied by wall height. Ceiling area, when selected, equals length multiplied by width. Direct-area rooms use the wall area entered. Door and window allowances are subtracted from the combined wall and ceiling area, never below zero. Gallons needed equal paintable square feet multiplied by the number of coats, divided by coverage per gallon; quarts equal gallons multiplied by four, and material cost equals unrounded gallons times the entered price.
Two-coat room example
A 12-by-15-foot room with 8-foot walls has 432 square feet of gross wall area. Subtract one 20-square-foot door and two 15-square-foot windows to get 382 paintable square feet. Two coats require 764 square feet of coverage. At 350 square feet per gallon, the estimate is 2.18 gallons, so the practical purchase may be three one-gallon cans depending on product and planned touch-up reserve.
Coverage assumptions that change the purchase
- Use the coverage printed for the chosen product; porous drywall, masonry, texture, and dramatic color changes can reduce real coverage.
- Primer is a separate material and is not included automatically in the finish-paint gallons.
- Round purchases by available container sizes and keep enough matching batch paint for touch-ups without buying a large excess.
Useful companion tools: Square Footage Calculator, Rehab Budget Calculator, ADU Cost Calculator, and Concrete Calculator.
How to interpret the paint result
Best use
Use the result to size a project, compare materials, estimate a reserve, or decide whether a contractor quote is in the expected range.
Cross-check
Compare the estimate with local code, site measurements, supplier pricing, utility bills, permit rules, and contractor scopes before buying materials.
Watch for
Project estimates are sensitive to waste, labor, access, climate, soil, and existing conditions. Add contingency when the job cannot be measured cleanly.
This page belongs to the Home & Construction calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.
Before relying on this paint estimate
Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.
Measure the actual site
Square footage, slope, access, waste, existing conditions, and local material availability can change a project estimate quickly.
Add contingency
Cuts, breakage, delivery issues, weather, permits, and hidden repairs often make the real budget higher than a clean calculation.
Compare with local pricing
Supplier quotes, contractor scopes, code requirements, and permit fees should control the final budget.
Rerun this page after new measurements, contractor quotes, material price changes, permit comments, or scope changes.
Sources used for this calculator
These primary or official references help define the rules, terminology, safety checks, or source documents behind this estimate. Source links were checked in July 2026. They do not turn the calculator output into a quote, appraisal, tax determination, or professional opinion.
- Renovation, Repair and Painting Program for consumers
U.S. Environmental Protection Agency
Review lead-safe requirements before disturbing painted surfaces in pre-1978 homes or child-occupied facilities.
How to Use
- Add one or more rooms and choose whether to calculate from dimensions or direct wall area.
- Enter room measurements or total square footage, then adjust doors, windows, and the ceiling option.
- Set your number of coats, coverage per gallon, and paint price per gallon.
- Review total wall area, paintable area, gallons needed, quarts needed, and your estimated cost.
Frequently Asked Questions
How many square feet does a gallon of paint cover?
A typical gallon of interior paint covers about 350 to 400 square feet per coat, depending on the paint type, surface texture, and how much the wall absorbs.
Should I include doors and windows in my paint estimate?
Yes. Subtracting doors and windows gives a more accurate estimate, especially across multiple rooms. A common rule of thumb is about 20 square feet per door and 15 square feet per window.
Do I need two coats of paint?
Usually yes. Two coats are common for color changes, new drywall, patchy surfaces, or when you want an even finish. One coat may be enough for touch-ups or when using high-hide paint over a similar color.
How do I estimate ceiling paint?
Ceiling area is usually length × width for each room. If you plan to paint the ceiling, include that area in addition to the wall area.
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