🎨How much paint do I need?
Let's figure out how much paint you need! Pop in your room size and we'll do the rest.
Your room
You'll need about
1.7 gallons
302 sq ft of wall · buy 2 cans to be safe
Buy one extra can if your walls are new, textured or a much darker colour — thirsty walls drink more paint!
Popular sizes & projects
Handy things for this job
We may earn a small commission from these links, at no extra cost to you.
How this paint calculator works
We measure the four walls of your room, subtract the doors and windows, then divide by how far a can of paint stretches.
- Wall area = (length + width) × 2 × wall height
- Subtract openings — about 20 sq ft per door and 15 sq ft per window
- Multiply by coats — most rooms need two
- Divide by coverage — a US gallon usually covers around 350 sq ft
Tips before you buy
- Buy a little extra for touch-ups later. A leftover half-can is cheaper than a second trip.
- Rough, porous or brand-new drywall soaks up more paint. Add 10–15% if your walls are thirsty.
- Going from a dark colour to a light one? Plan on a primer coat plus two top coats.
- Paint from the same batch where you can, so the colour matches perfectly.
Questions people ask
Most interior paints cover about 350 square feet per US gallon on a smooth, primed wall. Textured or unpainted surfaces can drop that to 250–300 square feet.
More calculators you might like
Baseboard & Trim Calculator
Work out linear feet and pieces of baseboard or trim for a room.
Deck Stain Calculator
Find out how many gallons of stain your deck and railings need.
Fence Stain Calculator
Find out how many gallons of stain your fence needs.
Wallpaper Calculator
Work out how many rolls of wallpaper you need, including pattern repeat.
Helpful guides
Email me my results
Pop in your email and keep your numbers handy at the store.
Last updated September 28, 2026. These results are friendly estimates to help you plan — always double-check before buying or making big decisions.