Paint Calculator
Work out how much paint a room needs from the wall area, the coverage printed on the tin and the number of coats you plan to apply.
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Formula and method
Wall area is multiplied by the number of coats, divided by the paint's coverage rate and increased by the waste percentage. The result is then rounded to a practical volume.
How to measure the inputs
- Measure each wall's length and height, then note how many walls share the same dimensions.
- Multiply length by height for one wall and let the calculator handle the wall count.
- Take the coverage rate directly from the tin, it varies a lot between products and finishes.
Worked example
Wall height 7.87 ft; Wall length 32.81 ft; Wall count 4; Number of coats 2; Coverage rate 10; Waste 10 % → Paint required: 1.47 US gal
Practical tips
- Buy all tins in the same batch and mix them together in a large container to even out shade.
- Two thin coats cover better than one thick coat and dry more evenly.
- Keep a small amount for touch-ups after furniture is moved in.