Question 1

How much paint do I need?

Accepted Answer

Multiply total paintable area by the coverage per gallon (or liter), then divide and multiply by the number of coats.

Question 2

What is typical paint coverage?

Accepted Answer

A common rule is 350-400 sq ft per gallon for smooth interior walls; rough or unprimed surfaces cover less.

Question 3

Do I subtract doors and windows?

Accepted Answer

Yes—subtract the area of large openings. Trim and edges add back a small amount for overlap.

Question 4

How many coats should I plan for?

Accepted Answer

Most projects need two coats; deep color changes or spot repairs may need a primer plus two coats.

Question 5

How does primer affect coverage?

Accepted Answer

Primer seals porous surfaces so finish coats cover closer to the rated value.

Paint Calculator — Room Paint & Coverage Calculator