Paint Calculator: Wall Area, Primer & Finish Containers
Estimate wall paint and primer separately using each product’s coat count, label coverage and container size.
Worked project: primer and finish paint are separate orders
- Measure a 12 ft × 10 ft room with 8 ft walls. Gross wall area = 2 × (12 + 10) × 8 = 352 ft². Subtract 40 ft² of doors and windows: 312 ft² of net wall area. Leave Include ceiling set to No.
- For this illustration only, enter finish paint coverage of 350 ft² per US gallon and 2 finish coats. Required finish paint = 312 × 2 ÷ 350 ≈ 1.7829 US gal. With 1 US gal containers, round to 2 finish-paint containers (2 US gal purchased).
- Enter primer coverage of 250 ft² per US gallon and 1 primer coat. Required primer = 312 ÷ 250 = 1.248 US gal. With 0.25 US gal containers (US quarts), round 1.248 ÷ 0.25 = 4.992 up to 5 primer containers (1.25 US gal purchased).
Keep the scope clear: Replace both illustrative coverage figures with the relevant product labels; they are not manufacturer claims. Round each product to its own container size, never combine primer and finish gallons into one order. Trim, surface-preparation materials and extra waste are excluded. If the ceiling needs a different product, calculate it separately rather than using the same-product ceiling option.
To reproduce this project, enter the values in the steps above. Reset to example values restores the calculator’s separate default example.
How this works
Surface area includes optional ceiling. Apply each product’s coat count and coverage, then round each product to its own container size.
Example
Using the example inputs, paint purchased in chosen containers is 2 gal.
- Room length
- 12 ft
- Room width
- 10 ft
- Wall height
- 8 ft
- Doors/windows area
- 40 sq ft
- Finish paint coats
- 2
- Finish paint label coverage
- 350 ft² / US gal
- Finish paint price per US gallon
- 0 USD / US gal
- Include ceiling
- No
- Primer coats
- 0
- Primer label coverage
- 350 ft² / US gal
- Finish paint container size
- 1 US gal
- Primer container size
- 1 US gal
- Primer price per US gallon
- 0 USD / US gal
- Paint purchased in chosen containers
- 2 gal
Finish paint and primer are separate products; cost uses whole chosen containers.
Scope and assumptions
Use product-label coverage. Trim, waste, surface preparation and differing wall/ceiling paint products are not included.
Related quantity-calculation reference