Paint Calculator
Free paint calculators for rooms, multiple rooms, exteriors, primer combos and project budgets — instant estimates in your browser.
Single Room Calculator
One room — walls, doors, windows, coats, waste, primer.
Multiple Rooms Calculator
A whole home or apartment — average room size across several rooms.
Exterior House Estimator
Siding, perimeter and height for the outside of the house.
Primer + Paint Combo
Both primer and top coat in one estimate, with color-change logic.
Paint Cost Calculator
Gallons, prices and tools turned into a project budget.
Coverage Reference Guide
How far a gallon goes on different surfaces.
Color Change Guide
When to add a coat or prime first for color changes.
Quick tips
- Standard coverage: 350-400 sq ft per gallon of latex paint.
- Walls, ceiling and trim each need their own totals — this tool focuses on walls.
- Dark-to-light color changes may need an extra coat or primer first.
- Always buy ~10% extra for touch-ups and mistakes.
Most common room sizes
| Room | Typical size | Wall area (8 ft ceiling) |
|---|---|---|
| Bedroom | 12′ × 12′ | 384 sq ft |
| Living room | 15′ × 18′ | 528 sq ft |
| Bathroom | 8′ × 10′ | 288 sq ft |
| Kitchen | 10′ × 12′ | 352 sq ft |
| Office | 10′ × 10′ | 320 sq ft |
| Master | 14′ × 16′ | 480 sq ft |
Wall area shown is before subtracting doors and windows — the calculators do that step for you.
Frequently Asked Questions
How do I calculate how much paint I need for a room?
Add the length and width, multiply by 2 for the perimeter, then multiply by wall height for gross wall area. Subtract doors (21 sq ft each) and windows (15 sq ft each), then divide by your paint's coverage per gallon and multiply by coats.
Do I need primer before painting?
Primer is recommended on new drywall, bare wood, stained or glossy surfaces, and for dramatic color changes. On previously painted smooth walls, two top coats usually work without primer.
How many coats of paint do I need?
Two coats are standard for even coverage. Dark-to-light or light-to-dark color changes often need a third coat or a quality primer first.
What is the difference between latex and oil-based paint?
Latex (water-based) dries fast, cleans up with soap and water, and is the standard for walls and ceilings. Oil-based (alkyd) is tougher and better for trim, but needs mineral spirits to clean up and has stronger fumes.
Why should I buy extra paint?
Buying about 10% extra covers touch-ups, mistakes, and coverage variations between brands. Running out mid-project means color-matching problems.