How do I calculate how much paint I need?

Measure your wall square footage (length × height for each wall), subtract for doors and windows, then divide by 350 (sq ft per gallon). Multiply by number of coats needed.

How much does one gallon of paint cover?

One gallon of paint typically covers 350-400 square feet with one coat on a smooth surface. Rough or porous surfaces may require more paint.

Do I need a primer before painting?

Primer is needed when painting bare drywall, going from dark to light colors, covering stains, or painting over a glossy surface. Self-priming paints can skip a separate primer coat.

How many coats of paint does a room need?

Most rooms need 2 coats. Going from light to dark or covering problem areas may require 3 coats. One coat is usually sufficient with high-quality paint on a well-primed surface.

Should I add extra paint for waste?

Yes, add 10% for waste and touch-ups. Buying an extra quart is recommended for future touch-ups using the same lot number and color.

Paint Calculator – DIY Calculators — Free Home Improvement Tools

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Quick Answer

To calculate how much paint you need, measure total wall square footage (length × height for each wall, minus doors and windows), then divide by 350 — the average square feet per gallon. For most rooms, plan for 2 coats and add 10% for waste and touch-ups.

Calculate exactly how much paint you need for any room. Accounts for doors, windows, and multiple coats.

Room Length (feet) Room Width (feet) Ceiling Height (feet) Number of Doors Number of Windows Number of Coats

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Paint Calculator. (2026). DIY Calculators Online. Retrieved from https://diycalculator.net/paint-calculator/

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