Paint Calculator for Room Walls
Calculate paint and primer for a rectangular wall from its dimensions, coats, coverage and waste allowance.
Formula
Planning estimate. Check product specifications and local requirements before purchasing.
Worked example: Paint Calculator
Measurements in this example
| Length | 5 m |
|---|---|
| Height | 2.7 m |
| Coats | 2 |
| Coverage | 10 m²/l |
| Waste allowance | 10 % |
Calculated quantities
| Area | 13.5 m² |
|---|---|
| Paint required | 3 l |
| Primer required | 1.4 l |
What to check
This calculation uses: Length, Height, Coats, Coverage, Waste allowance. It returns: Area, Paint required, Primer required.
This tool measures one rectangular wall, not a whole room perimeter. Calculate separate walls and colours independently. Primer is estimated for one coat using the same coverage value, without the paint allowance. Replace that estimate with the primer manufacturer’s coverage when it differs. The paint result includes the selected coats and allowance.
Coverage on the tin assumes a stated surface and application method. Porous repairs, strong colour changes and textured walls often need more.
Keep enough paint from the same mixed batch for the final coat. Confirm preparation, drying time and compatible primer before work.
Use the units beside each field. The values in the worked example are starting inputs; replace them with your measurements and the specifications of your material.
Compare alternatives
Open a tool, enter your measured dimensions, then save an estimate. Keep another version if you want to compare products or allowances.