Wall paint calculator
How much paint for this wall?
Enter your wall dimensions and any doors or windows in it — we'll subtract the openings and tell you how many gallons to buy.
Enter your room
We assume 350 sq ft of coverage per gallon (a typical mid-grade interior/exterior paint) — check your can's label and adjust if it differs.
Results
- Area to paint
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- Paint needed
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- Gallons to buy
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- Estimated cost
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Rounded up to whole gallons — paint stores don't sell partial cans.
Set width to 0 and length to your wall's length for a single wall, or use the room paint calculator for a full room.
How it's calculated
Length × height, minus openings.
With width set to 0, the perimeter formula (2 × length + width) reduces to 2 × your wall's length — covering both faces isn't relevant for a single interior wall, so this gives you one wall's area × height, minus doors and windows, × coats, ÷ coverage rate.
FAQ
Common questions
What's the difference between this and the room paint calculator?
Same formula — perimeter × height, minus doors and windows. Use this one when you're pricing a single wall or an accent wall: set doors/windows to 0 and enter just that wall's length as your "room length" with width set to 0, or use the plain paint calculator if you already know the square footage.
How much paint does an accent wall need?
The same coverage math applies — area × coats ÷ coverage rate. Accent walls often get 2 coats too, since a single bold color usually needs full opacity.
Do I need less paint for a wall with a lot of trim?
Trim and baseboards are usually painted separately in a different finish, so we don't subtract them here — only doors and windows, which are full openings rather than surface detail.
What if I'm painting multiple separate walls, not a full room?
Run each wall through the paint calculator with its own square footage, or add up each wall's length × height (minus openings) by hand and enter the total as a flat area in the paint calculator.