Paint for a 20×20 room
A 20×20 ft room with 8 ft ceilings has 640 sq ft of wall. For the standard 2 coats you need 4 gallons of paint (≈ $140 — a 5-gallon pail is usually cheaper).
| Wall area | 640 sq ft |
|---|---|
| 1 coat | 2 gal |
| 2 coats (standard) | 4 gal |
| 3 coats (big color change) | 6 gal |
| 2 coats, textured/bare walls | 6 gal |
| 2 coats + ceiling | 6 gal |
| Estimated cost (2 coats) | ≈ $140 |
Adjust it
Change the size, ceiling height, coats, or surface below:
How much paint do I need?
| Paintable area | |
|---|---|
| Coverage needed (with coats) | |
| Estimated paint cost |
Estimate for walls (2 coats by default). Coverage assumes smooth, primed drywall; bare or textured walls absorb more — pick "Textured." Small doors/windows are left in as a cut-in buffer. Cost is an estimate (as of June 2026) — confirm the price of your chosen paint.
The math: wall area = 2 × (20 + 20) × 8 = 640 sq ft; × 2 coats = 1,280 sq ft; ÷ 350 sq ft per gallon (smooth drywall) = 3.66 → round up to 4 gallons. Read the full guide: How much paint do I need?
Other room sizes
Last updated: 2026-07-03.
Coverage from Sherwin-Williams
(350–400 sq ft/gal smooth drywall) and Behr guidance. Cost is a US-average estimate.