How Much Paint Do I Need? A Room-by-Room Guide
Buy too little and you're back at the store hoping the next batch matches. Buy too much and you've got $50 worth of paint drying out in your garage. Here's how to get the right amount the first time.
Skip the Math
Enter your room dimensions and get instant gallons needed with cost estimate.
Paint CalculatorThe Basic Formula
Add up all your wall lengths to get the perimeter. Multiply by ceiling height. That's your total wall area. Subtract 21 sq ft per door and 15 sq ft per window. Multiply what's left by how many coats you're doing, then divide by 350 (standard coverage per gallon). Round up. Always round up.
Coverage Rates by Surface Type
Smooth, already-painted walls: 350-400 sq ft per gallon. What the can says, accurate if your walls are in decent shape. Textured walls (knockdown, orange peel, popcorn): 250-300 sq ft. All those bumps create more surface area than you'd think. New drywall: 300-350 sq ft for primer, then standard rates. Always prime new drywall. Always. Brick or masonry: 150-200 sq ft. Brick drinks paint.
Room-by-Room Estimates
| Room | Typical Size | Gallons (2 coats) |
|---|---|---|
| Bedroom (12x12 ft) | 384 sq ft walls | 2 gallons |
| Living Room (14x18 ft) | 512 sq ft walls | 3 gallons |
| Bathroom (8x10 ft) | 288 sq ft walls | 1-2 gallons |
| Kitchen (12x14 ft) | 416 sq ft walls | 2-3 gallons |
| Hallway (4x20 ft) | 384 sq ft walls | 2 gallons |
| Ceiling (12x14 ft) | 168 sq ft | 1 gallon |
These assume 8-foot ceilings and two coats on smooth walls. Add a gallon if you've got texture, you're going from dark to light, or you want extra for future touch-ups (you should).
When Do You Need Extra Paint?
Dark to light? Plan on three coats or tinted primer plus two. Raw drywall? It soaks up the first coat like a sponge. Textured? Add 15-25% more than the standard estimate. Touch-ups: Keep at least a quart. Seal it, store it cool, label it with the room and date. Future you will be grateful.
Paint Cost Estimates
Budget paint: $20-30/gallon. Mid-range (Behr, Valspar, Glidden): $30-50. Premium (Benjamin Moore, Sherwin-Williams Duration, Farrow & Ball): $50-100+. A typical bedroom takes 2 gallons, so you're looking at $40-$200 depending on what you pick. The premium stuff does cover better (sometimes saving you a coat), lasts longer, and cleans easier. Whether that's worth 3x the price is up to you. The Paint Calculator estimates cost at $40/gallon as a mid-range baseline. For other home improvement planning, the Concrete Calculator covers outdoor projects and the Paver Calculator estimates materials for patios.