Paint Calculator

This paint calculator estimates how many liters or gallons of paint a room needs from wall area and coats.

Formula notes

paintable area = perimeter × height − openings; liters = area × coats / coverage per liter (typically 10–12 m²/L).

Worked examples

1. Example: a 5 m × 4 m room with 2.5 m ceilings has 45 m² of wall; two coats at 10 m²/L needs 9 L of paint.
2. If net wall area is 70 m2, two coats require 140 m2 of coverage; paint rated at 10 m2/L therefore needs about 14 L before contingency.

How to use it

1. Enter room dimensions and ceiling height.
2. Subtract doors and windows if the tool asks.
3. Set the number of coats and read liters needed.

Frequently asked questions

Limits and interpretation

• Coverage changes with surface porosity, texture, colour change, application method, and the specific product.
• Doors, windows, trim, ceilings, primer, spillage, and container-size rounding must be handled explicitly.

References

• NIST: SI Units