Room paint calculator
Estimate paint for rectangular room walls, optional ceiling, openings, coats and the coverage printed for the selected paint.
How to use this calculator
How to measure
Measure length, width and wall height, then total doors and windows not being painted. Copy coverage per litre and container size from the exact paint label or data page.
Worked example
Walls with 32 m² net area and two coats create 64 m² coated area. At 8 m²/L, 8 L are required; 2.5 L cans require 4 cans, or 10 L purchased.
Formula and purchasing method
walls = 2 × (length + width) × height − openings; coated area = (walls + optional ceiling) × coats; litres = coated area ÷ label coverage; containers = ceil(litres ÷ container size).
Assumptions
- Walls are rectangular and share one height.
- Published coverage is entered per coat for the selected product.
Limitations
- Porosity, colour change, application loss and primer can alter real coverage.
- Trim, doors, radiators and repairs are excluded unless their areas are modeled.
FAQ
Should I always subtract windows?
Subtract only surfaces that will not be painted with this product.
Is the typical coverage a guarantee?
No. Use the selected product data and treat the result as an estimate because surface and application matter.
Sources
Product-specific values must be copied from the exact current label or technical datasheet; linked examples document the method and its limits.
Calculation privacy
Calculations run locally. Form inputs and results stay in your browser.
How storage works and how to delete data