Spray cans = area × coats ÷ coverage per can, plus waste. A 40 sq ft surface with two coats at 25 sq ft per can and 10% waste needs 3.52 cans, so buy 4. The coverage is the figure printed on the can, for a single coat.
How many cans of spray paint
cans = area × coats × (1 + waste %) ÷ coverage per can, rounded up
Krylon prints 25 sq ft of coverage on its 12 oz Fusion All-In-One can, which is a 5 × 5 ft square. Other brands and lines print less: read the label of the can you buy and type it into the coverage field. Add a coat if you prime first, using the primer toggle. Two light coats cover better than one heavy coat, so the default is two.
Spray paint coverage
At 25 sq ft per can with 10% waste:
| Area | 1 coat | 2 coats | 3 coats |
|---|---|---|---|
| 10 sq ft | 1 can | 1 can | 2 cans |
| 20 sq ft | 1 can | 2 cans | 3 cans |
| 40 sq ft | 2 cans | 4 cans | 6 cans |
| 80 sq ft | 4 cans | 8 cans | 11 cans |
Worked example: 40 sq ft, two coats
| Step | Calculation | Result |
|---|---|---|
| Paint area | 40 sq ft × 2 coats | 80 sq ft |
| With 10% waste | 80 × 1.1 | 88 sq ft |
| Cans | 88 ÷ 25 | 3.52 |
| Buy | round up | 4 cans |
With a primer coat, the same job is three coats: 40 × 3 × 1.1 ÷ 25 = 5.28, so 6 cans.
Spray painting several sides
Enter the length and width of a flat surface, then the number of sides: a table top and its underside is 2, a panel painted on both faces is 2. If the piece has legs, spindles or a lattice, measure it as separate flat pieces and add them with the total-area mode. Spray paint on open work such as lattice or a wire shelf wastes more into the air, so raise the waste allowance.
What changes the coverage
The can's number is for one coat on a smooth, primed surface. Bare wood, rough or porous surfaces, and heavy textures drink more paint, and a windy or cold spray day wastes more. Krylon says its Fusion paint is dry to the touch in about 20 minutes and ready to handle in an hour; follow the label for recoat times.
The next questions
- Staining wood instead of painting? Use the stain calculator.
- Painting walls or a whole room with a roller? The paint calculator and exterior paint calculator work in gallons.
- Need the area first? Use the square footage calculator.
- Coating a floor? See the epoxy calculator.
- See every wall, ceiling and paint calculator.