Paint Calculator (How Much Paint Do I Need?)
Paint calculator: liters or gallons of paint for your walls from the area, number of coats and coverage.
V = A · nc
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
Paint needed = area × coats ÷ coverage. Subtract doors (≈ 2 m² / 21 ft²) and windows.
Typical wall paint covers 350–400 ft² per gallon (about 10 m² per liter).
Formula
V = A · nc
| Symbol | Quantity | Units |
|---|---|---|
| A | Wall area (minus doors and windows) | m², km², cm², mm², ha, ft², in², yd², ac, mi² |
| n | Number of coats | — |
| c | Coverage, m² per liter | — |
| V | Paint needed | L, mL, µL, m³, dm³, cm³, gal, gal (UK), qt, pt, cup, fl oz, ft³, yd³, in³ |
Constants used: Typical coverage: 350–400 ft² per gallon (≈ 10 m²/L)
Worked example
Given: A = 430.556 ft² · n = 2 · c = 10
V = A nc
Result: V = 2.11338 gal
Paint needed for different values of Wall area (minus doors and windows)
| A · Wall area (minus doors and windows) | V · Paint needed |
|---|---|
| 215.3 ft² | 1.0567 gal |
| 322.9 ft² | 1.585 gal |
| 387.5 ft² | 1.902 gal |
| 430.6 ft² | 2.1134 gal |
| 473.6 ft² | 2.3247 gal |
| 538.2 ft² | 2.6417 gal |
| 645.8 ft² | 3.1701 gal |
| 861.1 ft² | 4.2268 gal |
Other values as in the worked example.
Frequently asked questions
Paint for 400 ft² with 2 coats at 350 ft²/gal?
About 2.3 gallons.
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