A free paint calculator that works out the gallons or liters a room takes, less doors and windows.
See how much paint a room takes for the coats you want, less doors and windows.
Your numbers
The coverage is on the can's label. Take off the doors and windows you won't paint.
Your result
Fill in the fields above to see your result.
Embed this tool on your site
Paste the code into any page: WordPress, Webflow, Squarespace, Ghost or plain HTML. It's free with the credit under it, which links back to navid.me.
This free paint calculator works out how much paint a room's walls take, in gallons or liters, for the coats you want.
It takes off the doors and windows, and uses the coverage printed on your can.
I built it because paints cover different areas, so a fixed rule of thumb can leave you a can short, or with 2 spare.
Here's the formula, a worked example, and where to find the coverage.
TL;DRKey takeaways
What is a paint calculator?
A paint calculator turns a room's size into the paint its walls take.
It counts every coat, and leaves out what you won't paint.
How paint is worked out
The walls make a band around the room: the room's perimeter times the wall height.
A worked example
Here's the example the calculator loads: a 14 by 12 foot room, 8 foot walls, 40 square feet of doors and windows, 2 coats and 350 square feet a gallon.
2 × (14 + 12) × 8 = 416 square feet. Less 40, that's 376. × 2 coats = 752. ÷ 350 = 2.15 gallons, about 8.1 liters.
Where to find the coverage
The can's label lists the coverage a gallon or a liter. If it gives a range, the low end is the safe pick.
Mistakes to avoid
These are the slips that come up most.
- Forgetting the second coat
- Leaving the doors and windows in
- Using another paint's coverage
Who is the paint calculator for?
It's for anyone painting a room, and these tools help around it.
- Wallpaper calculator – for papering a wall instead
- Square footage calculator – for a ceiling's area
- Flooring calculator – for the floor
Buy the paint once, and every wall gets the same batch.
Plan your money with your AI
Take your numbers further in
Paint Calculator FAQs
Questions about the paint calculator? Here's what to know.
A paint calculator works out how much paint a room's walls take, in gallons or liters.
Multiply the wall area, less doors and windows, by the coats, and divide by the can's coverage.
With 8 foot walls and 2 coats at 350 square feet a gallon, about 2.2 gallons before doors and windows.
Multiply each one's width by its height, and add them up.
On the can's label, as square feet a gallon or square meters a liter.
A US gallon is about 3.785 liters.
Yes, a ceiling's area is the floor's area, so use the square footage calculator and the can's coverage.
Yes, it's free with no sign-up.
It runs in your browser, and your numbers stay on your device.
I did.
I'm Navid Moazzez, and I made the paint calculator as one of my free tools on navid.me.
More about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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