How to use the paint estimate
Compare the raw paint need with the rounded units to buy. If you are changing from a dark color to a light color, painting porous surfaces or skipping primer, the real number of coats may be higher.
Example
For 800 square feet, 2 coats, 350 square feet per unit and 10% waste, raw need is about 5.03 units. If paint costs $35 per unit, buying 6 units costs about $210 before primer.
Common mistakes
Do not forget primer, trim paint, ceiling paint, tools and taxes if you are budgeting the whole job rather than only wall paint.
Practical assumptions
Paint coverage varies by surface, color change, primer, roller type and product label. Use the paint can label as the authority and keep a waste buffer for touch-ups.
Last reviewed: 2026-05-17