Paint
Calculator
Plug in your room dimensions. Get gallons (or liters) needed, plus what it'll cost.
Enter your room dimensions above to get your paint estimate.
The math, briefly
Perimeter (2 × length + 2 × width) times height gives total wall area. Subtract about 21 sq ft per door and 15 sq ft per window. Multiply by the number of coats, divide by 400 — that's how much a gallon covers on smooth, primed walls. Cost estimate uses $30–$50 a gallon to cover budget through premium.
Frequently asked questions
Frequently Asked Questions
Q1 How much paint do I need?
Depends on the room. Measure length, width, and wall height (standard is 8 ft / 2.4 m). Multiply the perimeter by the height for total wall area, subtract doors (~21 sq ft each) and windows (~15 sq ft each), divide by 400 sq ft per gallon, multiply by the number of coats. The calculator above does all that.
Q2 How far does a gallon go?
About 350–400 square feet on smooth, primed walls. Rougher or unpainted surfaces eat more — closer to 250–300. Always grab 10% extra for touch-ups.
Q3 How many coats?
Two is standard. Three if you're going dark over light or covering a bold existing color. Add a primer coat for big color changes or new drywall.
Q4 How much does paint cost?
$25–$50+ a gallon. Budget around $25, mid-range $30–40, premium (Benjamin Moore, Sherwin-Williams) $40–60+. Better paint often covers in fewer coats, which closes the price gap.
Q5 What about the ceiling?
This counts walls only. For ceiling, multiply length × width, divide by 400, add that to your total.
Q6 Can I see the color on my wall first?
Yes — open the Intero app, upload a photo of the room, and you'll see the color on your real walls before you crack a can.
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