How to Measure a Room for Paint
Learn how to measure a room for paint. Step-by-step guide to calculate wall area, account for doors and windows.
Getting measurements right is the difference between one trip to the store and three. You don't need to be a pro — you just need to measure the right things and not round the numbers to death.
What You Need
- 25-foot tape measure — locking blade is worth the extra few bucks. The $10 one from Home Depot does the job.
- Something to write on — paper, phone notes app, whatever works.
- Step ladder — for ceiling height. A chair works in a pinch but don't be a hero.
- Calculator — your phone or a paint calculator will do the heavy lifting.
Step by Step
1. Length and Width
Start in one corner. Hook the tape's metal tab against the baseboard where it meets the corner. Run it to the opposite corner. Write the number in feet. Round to the nearest inch — that's 0.1 ft per inch. Repeat for the width.
If your room is 12 feet 4 inches, write 12.3 ft (4 inches = 0.33 ft). Don't round to 12 or 13 — small errors multiply across four walls real fast.
2. Ceiling Height
Most houses have 8-foot ceilings. Newer builds often have 9-foot. Don't guess — measure floor to ceiling in at least two spots. Floors settle and ceilings aren't always dead level. Have someone hold the bottom of the tape if you can.
3. Doors and Windows
Measure width × height for every door. Standard interior door is 3' × 7' = 21 sq ft. For windows, measure the glass plus the frame. Typical window: about 3' × 5' = 15 sq ft. Don't eyeball it — measure each opening individually.
4. The Weird Stuff
- Fireplaces: Measure the surround and subtract from wall area.
- Built-in shelving: Measure the wall area behind them.
- Archways: Treat them like door openings.
- Wainscoting or chair rails: Measure the wall above and below separately.
- Sloped ceilings: Measure the tallest and shortest points. Use the average.
Quick Room Size Cheat Sheet
| Room Type | Typical Size | Wall Area (8' ceiling) |
|---|---|---|
| Small bathroom | 5' × 8' | ~208 sq ft |
| Standard bedroom | 12' × 12' | ~384 sq ft |
| Master bedroom | 15' × 15' | ~480 sq ft |
| Living room | 18' × 14' | ~512 sq ft |
| Kitchen | 12' × 10' | ~352 sq ft |
Measuring Mistakes That Cost You
- Rounding too hard: Rounding 11'8" to 12' adds 4 inches per measurement — over a foot of error across four walls.
- Forgetting the closet: A walk-in closet is significant wall area. Count it.
- One measurement for weird rooms: L-shaped and irregular rooms need to be broken into rectangles.
- Measuring baseboard to baseboard: That misses the wall area above. Measure floor to ceiling.