Paint coverage by room size
Use this table for a fast planning check, then use the Paint Calculator for your exact room. These examples use the same published formula as the calculator.
Published August 30, 2026 · Reviewed September 3, 2026 · Method: BetterHomeHabits calculator model
For a typical rectangular room with 8-foot walls, two coats and standard openings, many common bedrooms require roughly 2–3 gallons of wall paint. Exact needs change with room perimeter, openings, coats and the coverage printed on the paint can.
Reference table
| Room size | Net wall area | Calculated paint | Whole gallons to buy |
|---|---|---|---|
| 10 × 10 ft | 269 sq ft | 1.69 gal | 2 gal |
| 10 × 12 ft | 301 sq ft | 1.89 gal | 2 gal |
| 12 × 12 ft | 333 sq ft | 2.09 gal | 3 gal |
| 12 × 15 ft | 381 sq ft | 2.39 gal | 3 gal |
| 15 × 20 ft | 509 sq ft | 3.20 gal | 4 gal |
| 20 × 20 ft | 589 sq ft | 3.70 gal | 4 gal |
Assumptions used
- 8 ft wall height
- 1 standard door (21 sq ft)
- 2 standard windows (15 sq ft each)
- 2 coats
- 350 sq ft coverage per gallon
- 10% waste allowance
Why your result may differ
Texture, porosity, repairs, primer use, color change, actual openings and label coverage can change gallons. Recalculate with the selected paint rather than treating the table as a product guarantee.
Methodology
Each row calculates wall perimeter × 8 ft, subtracts one 21 sq ft door and two 15 sq ft windows, applies two coats and 10% waste, then divides by 350 sq ft per gallon.