Free paint calculator
How much paint do you need? Find out in seconds
Enter your room, subtract doors and windows, choose your coats and can size. The calculator shows the paint you need, the cans to buy and the cost. Painting for clients? The iPhone app adds room scanning, saved jobs and PDF quotes.
- Gallons or litres
- Doors & windows deducted
- Cans to buy & cost
Paint calculator
Enter one room's measurements. Change the number of rooms to repeat it, or tick the ceiling to include it.
Paint required
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Buy
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- Paintable area
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- Wall area after openings
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- Ceiling area
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- Openings deducted
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- Estimated cost
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Coverage varies by paint and surface. Check the can label and use the lower figure for rough or porous walls.
Painting for a living? The app scans rooms to measure walls, saves estimates into job folders, adds labour and mark-up, and exports PDF or Excel quotes.
Download on theApp StoreMore than a calculator
Scan to measure
Scan a room with your iPhone and tap the walls to include or remove. No tape measure needed.
Exact paint & cans
Coverage, coats and waste allowance turn into the litres or gallons you need and the cans to buy.
Budget the cost
Enter the price per can and see the estimated cost before you get to the shop.
PDF & Excel reports
Export a client-ready PDF report or an editable Excel sheet in seconds.
Jobs in folders
Keep every room and project organised, and reuse previous estimates.
Imperial or metric
Square feet and gallons or square metres and litres. Works anywhere.
Buy the exact paint amounts you need
Painting guides
How Much Paint Do I Need? (Simple Formula + Calculator)
Work out exactly how much paint you need for any room: the formula, worked examples in gallons and litres, and how to turn it into cans to buy.
Read guide →How Many Square Feet Does a Gallon of Paint Cover?
A gallon of paint covers about 350–400 sq ft per coat, but surface, color and paint type change that. Here's a coverage table and how to use it.
Read guide →How Much Paint for a Room? (12x12, 10x10 and More)
How many gallons of paint you need for common room sizes, with and without the ceiling, plus a quick way to calculate any room.
Read guide →How Much Does It Cost to Paint a Room?
Typical costs to paint a room yourself or with a professional, what drives the price, and how to estimate your own room in two minutes.
Read guide →Cost to Paint a House Interior (and How to Estimate It)
What it typically costs to paint the inside of a house, per square foot and per room, and a step-by-step way to estimate your own home.
Read guide →Cost to Paint a House Exterior (2026 Guide)
What drives the cost of painting the outside of a house, typical price ranges, and how to measure the exterior to estimate paint and labor.
Read guide →Interior Painting Cost per Square Foot
How painters price interior work per square foot, the difference between floor and wall square footage, and how to estimate a job with a per-foot rate.
Read guide →How to Estimate a Paint Job (Step-by-Step for Painters)
A practical method for painters to estimate interior and exterior jobs: measuring, paint quantities, labor hours, materials and mark-up.
Read guide →Painting Quote Template: What to Include
What a professional painting quote should include, with a sample layout, plus tips that help painters win more jobs.
Read guide →How Much Paint Do I Need for a Ceiling?
How to calculate ceiling paint: area, coats and coverage, with quick numbers for common room sizes and tips for textured ceilings.
Read guide →How Much Primer Do I Need?
When you need primer, how to calculate how much, and typical primer coverage for drywall, wood and stained surfaces.
Read guide →How Much Paint for Kitchen Cabinets?
How to estimate paint and primer for kitchen cabinets, typical amounts for an average kitchen, and why cabinet paint is different.
Read guide →How Much Paint for a House Exterior?
Measure the outside of your house and calculate the gallons of exterior paint you need, with a worked example and coverage tips.
Read guide →How Much Paint per m²? Litres per Square Metre Explained
How many litres of paint you need per square metre, typical coverage for emulsion and masonry paint, and how to work out tins for a room.
Read guide →How Many Coats of Paint Do You Need?
When one coat is enough, when you need two or three, and how the number of coats changes the amount of paint to buy.
Read guide →How Much Paint or Stain for a Fence? (Fence Paint Calculator)
Work out how much paint or stain your fence needs: measure both sides, allow for rough timber, and turn it into litres or gallons with worked examples.
Read guide →Painter and Decorator Prices: How to Work Out a Fair Quote
How painters and decorators price work, typical UK day rates and room prices, and how to check a quote using your room's real paintable area.
Read guide →Frequently asked questions
How much paint do I need for a room?
Measure the perimeter of the room and multiply by the wall height, subtract about 21 sq ft per door and 15 sq ft per window, multiply by the number of coats and divide by the coverage on the can (usually 350–400 sq ft per gallon). A 12×12 ft room with 8 ft walls needs about 2 gallons for two coats.
How many square feet does a gallon of paint cover?
Most interior paints cover about 350–400 square feet per gallon per coat on smooth, primed walls. Textured, porous or dark surfaces can drop that to 250–300 square feet.
Is the paint calculator free?
Yes. The calculator on this page is free with no sign-up. The iPhone app's core calculator is also free; room scanning, PDF quotes and job tools for painters are part of Pro.