Paint Calculator
Work out how many gallons or quarts of paint a room needs before you buy. Enter the room dimensions and the calculator subtracts standard doors and windows, applies your number of coats, and divides by the coverage rate printed on the can.
Area to paint
301 sq ft
Gallons needed
2 gal
Quarts needed
7 qt
Estimated paint cost: $90.00 (2 gallons at $45.00 each)
How to use this paint calculator
- Enter the room length, width and wall height.
- Set the number of coats — 2 is typical for a colour change.
- Enter how many doors and windows the room has.
- Tick 'include ceiling' if you are painting the ceiling too.
- Adjust the coverage rate if your paint can states a different figure.
- Read the gallons needed, quarts needed and the estimated cost.
Frequently asked questions
How much does a gallon of paint cover?
Most interior paints cover about 350–400 square feet per gallon on smooth walls. Textured or porous walls absorb more, so use a lower coverage rate such as 300.
Do I need to subtract doors and windows?
Yes, otherwise you buy paint you will never use. This calculator deducts about 21 sq ft per standard door and 15 sq ft per window.
How many coats of paint do I need?
One coat is often enough for a touch-up in the same colour. Two coats is the standard for a colour change, and three is wise over dark or heavily patched walls.
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