Paint calculator.
Estimate paint containers from measured area, coats and the coverage on your product label. See required paint and purchased surplus.
Your inputs
Use measurements from your plan and properties from your chosen product. Any prefilled values are illustrative.
A clear estimate starts here.
Enter your dimensions and product details to see the quantity and purchase breakdown.
How to use this paint calculator
Find how much paint to buy from your measured wall or ceiling area and the coverage per coat stated for the selected product. Whole containers are rounded after combining coats and your allowance.
- Enter the surface area you will actually coat. Use the room surface tool to deduct measured openings.
- For a whole room or several rooms, the Paint a Room project combines their surfaces and optionally includes ceilings.
- Enter coverage per coat from the product label, the number of coats and container volume.
- Read both required and purchased paint. Their difference is surplus from rounding to whole containers.
Formula and assumptions
How this calculation works.
Calculate each paint and primer separately with its own coverage. Coats are your input, not a product recommendation. Round to whole containers only after multiplying area by coats and applying the allowance. The room project combines wall and optional ceiling areas before this rounding. Coverage per coat must come from the selected product and application conditions.
A worked example
Illustrative inputs only. Product properties and design dimensions are not recommendations for your project.
- Surface area
- 50 m²
- Product coverage per unit
- 10 m²/L
- Number of coats
- 2
- Container size
- 5 L
- Waste allowance
- 10 %
Containers to purchase: 3 containers
A small area change can cross a whole-container boundary
Required liquid depends on net surface area, your selected coats and product coverage. Whole containers may leave surplus even when the measurements are exact.
- Subtract measured openings once and calculate primer separately using its own coverage.
- Confirm coverage and container volume on the actual product. Coverage per coat and volume are different inputs.
- If the estimate is close to a pack boundary, review measurements before changing the allowance.
What changes when one measurement changes?
Using the worked example above, change only surface area from 50 to 75m². Product specifications and all other inputs stay the same.
Containers to purchase: 3 → 4containers
Both results are computed by the same current calculator engine. These are illustrative dimensions, not material or design recommendations.
Calculation version and responsibility
Formula version: 1. Input schema: 1. Output schema: 2. Material data: user-supplied. Safety text: 1.
The method uses your dimensions and supplied product properties. Software tests check arithmetic examples and validation; this does not establish professional review of a design. Read the calculation policy.
Before you purchase
Use dimensions from your plan and properties from your chosen product. Any design spacing, section or fixing pattern must already be specified.
Method: dimensional arithmetic and user-supplied specifications. Software checks: 2026-10-03. Calculation and review policy.
A US unit example
A measured 400 ft² surface at an illustrative product coverage of 350 ft² per US gallon, two specified coats and zero allowance requires 400 × 2 ÷ 350 = 2.2857 US gallons. In 1 US gallon containers, the order is 3 containers with 0.7143 US gallon surplus. Coverage and coats are illustrative product inputs.
Common questions
How much paint do I need for two coats?
Multiply measured surface area by two, then divide by the product coverage per coat. Apply an allowance only once, then round to the selected container volume.
Can exterior and interior paint use the same coverage?
Use the label for the selected product, application method and surface. The Exterior Paint Calculator measures several facades, including triangular gables and openings.
Does paint coverage include ceilings?
The area-based form uses exactly the area you enter. The Paint a Room project lets you include or exclude ceilings before calculating containers.