Calculateur de peinture

Paint Calculator

This paint calculator estimates how much paint you need for walls and ceilings based on room dimensions, number of coats, and paint coverage. It helps you avoid under-buying or over-buying and gives you a realistic material budget before starting the job.

How Paint Coverage Is Estimated

The calculation starts with surface area:

Wall Area = 2 x (Length + Width) x Height

Then openings are subtracted:

Paintable Area = Wall Area - Door/Window Area

Finally, coats are applied:

Total Coverage Needed = Paintable Area x Number of Coats

If you enter paint coverage per gallon and price per gallon, the calculator also returns gallons required and estimated cost.

Example

Room	Paintable Area	Coats	Coverage Needed	Gallons (350 sq ft/gal)
12 x 15 x 8 ft	378 sq ft	2	756 sq ft	2.2 (buy 3)
10 x 10 x 8 ft	304 sq ft	1	304 sq ft	0.9 (buy 1)
14 x 20 x 9 ft	576 sq ft	2	1,152 sq ft	3.3 (buy 4)

What Changes the Final Amount Most

• Number of coats: Going from one to two coats usually doubles paint needs.
• Wall texture: Rough surfaces consume more paint than smooth drywall.
• Color change: Dark-to-light transitions may require an extra coat.
• Coverage rating: Premium paints can have higher coverage and better hide.

Tips

1. Round up to full gallons and keep at least one extra quart for touch-ups.
2. Check manufacturer coverage on the exact product you plan to buy.
3. Include primer separately when switching to lighter colors or painting raw drywall.
4. Track room-by-room estimates so you can batch purchases and reduce waste.