OverCalculator
  1. Home
  2. Construction & Home
  3. Paint Calculator
Construction & Home

Paint Calculator

Calculate how much paint you need for your project with this comprehensive paint calculator for walls, ceilings, and trim.

Paint needed
Paint to buy
2 gallons
Total area
352.00 sq ft
Net area
302.00 sq ft
Coverage
400 feet² per gallon
Coats
2 coats

Assumes 15 feet² per window, 20 feet² per door, and rounds up to whole gallons of eggshell paint.

ft
ft
ft

Results update as you type.

Paint Calculator

Estimate how many whole gallons of paint to buy for walls, ceilings, or trim. The calculator uses room length, width, height, measurement unit, paint finish, coats, identical rooms, windows, and doors to estimate total area and net paintable area.

How to use this calculator

Choose the surface type, measurement unit, paint finish, and number of coats. Enter room dimensions, identical room count, windows, and doors. Results show paint to buy, total area, net area, coverage, and coats. For flooring or wall surface planning, compare area with the square footage calculator.

Formula

The existing formula is:

gallons=area×coats÷coveragegallons = area \times coats \div coverage

For walls, gross area is twice length times height plus twice width times height. A 12 ft by 10 ft by 8 ft room has 352 sq ft of wall area. With 2 windows and 1 door subtracted, net area is 303 sq ft. Two coats at 350 sq ft per gallon rounds up to 2 gallons.

Painting tips

Buy all gallons for a color at the same time when possible, and keep leftover paint for touch-ups. Trim and ceilings often need separate finishes. For tiled surfaces or backsplashes near painted walls, use the tile calculator.

Frequently asked questions

How many gallons of paint do I need for a room?
Enter surface type, room dimensions, openings, identical rooms, and coats. The calculator subtracts windows and doors for walls and rounds up to whole gallons.
Does this paint calculator include ceilings and trim?
Yes. Choose walls, ceiling, or trim as the surface type. Each option uses a different area formula.
What coverage per gallon does it use?
The calculator uses its built-in coverage value for feet or meters and shows the coverage in the results.
Are windows and doors subtracted from paint area?
Yes for the wall calculation. It subtracts assumed areas per window and door before multiplying by rooms and coats.

Related calculators

Bathroom Mirror Size Calculator Find a comfortable bathroom mirror size based on vanity width, ceiling height, lights, and design spacing. Brick Calculator Calculate the number of bricks needed for your construction project. Includes mortar calculations, wastage estimates, and detailed layout information. Cable Size Calculator Calculate the appropriate electrical cable size based on current, voltage, distance, and installation conditions. Compost Calculator Calculate the exact amount of compost needed for your garden, lawn, or raised bed. Get volume estimates, cost calculations, and application guidelines. Concrete Calculator Calculate the volume of concrete needed for your construction project. Supports various shapes including slabs, columns, tubes, curbs, and stairs. Concrete Volume Calculator Calculate concrete volume, materials, and cost estimates for construction projects including slabs, footings, and walls

Paint Calculator updated at