Paint Calculator - How Much Paint Do I Need
Calculate how many gallons or liters of paint you need from wall dimensions, number of coats, and coverage rate.
Walls
Total Wall Area
198 sq ft
Paint Needed
1.13 gallons
How to Calculate How Much Paint You Need
Add each wall you plan to paint with its length and height, choose how many coats you'll apply, and set your paint's coverage rate (how much area one gallon or liter covers). The calculator totals the wall area, multiplies by the number of coats, and divides by your paint's coverage rate to tell you how much paint to buy.
This doesn't subtract door or window area — for a more precise estimate, reduce a wall's height/length slightly or remove large openings from the total manually.
Example
Two walls measuring 12×9 ft and 10×9 ft give a total area of 108 + 90 = 198 sq ft. With 2 coats and a paint that covers 350 sq ft per gallon, you'd need (198 × 2) / 350 = 1.13 gallons.
Common Use Cases
- Estimating how many gallons or liters of paint to buy for a room or set of walls.
- Planning paint quantities for a multi-coat job before heading to the store.
- Budgeting a painting project by knowing exactly how much material is required.
FAQs
What coverage rate should I use?
Check the paint can label — most interior paints cover roughly 350-400 sq ft per gallon (about 8-10 m² per liter) for a single coat, though rougher or more porous surfaces reduce coverage. Adjust the coverage field to match your specific paint.
Should I round up the final amount?
Yes — paint is sold in fixed can sizes, so round the result up to the nearest can size (e.g., a gallon or a liter) and consider a small buffer for touch-ups or an uneven surface.
Do ceilings count as walls here?
You can add a ceiling as an extra row using its length and width as the two dimensions — the calculator just multiplies the two numbers you enter, so it works for any flat surface.