Paint Calculator
Last updated: 2026-06-25
Paint needed (L) = (paint area × coats) ÷ coverage rate × (1 + waste rate). Coverage rate defaults to about 10 m²/L for one coat of water-based paint.
Example) Area 40 m², 2 coats, 10 m²/L, 5% waste: (40 × 2) ÷ 10 × 1.05 = 8.4 L → about 9 L needed.
Enter painting details
Paint needed
0 L
| Item | Value |
|---|---|
| Entered area (1 coat) | |
| Number of coats | |
| Total painted area | |
| Coverage rate | |
| Amount needed (incl. waste, rounded up) |
Results are a reference estimate based on a typical coverage rate. Coverage varies by surface and product, so check the coverage rate on the product spec sheet.
How to use
- Enter area — Enter the total wall and ceiling area to be painted in square meters (m²).
- Enter coats and coverage rate — Enter the number of coats (usually 2), the coverage rate (default 10 m²/L), and the waste rate.
- View the result — Click calculate to see the total painted area and the amount of paint (L) and recommended purchase amount.
How to calculate how much paint you need
The amount of paint needed is found by multiplying the area by the number of coats to get the total painted area, then dividing by the paint's coverage rate (the area one liter covers). A waste rate is then added to account for brush and roller loss.
Coverage rate varies by product, but standard interior water-based paint covers about 10 m² per liter for one coat. Rough, absorbent surfaces and dark colors lower the coverage and increase the amount.
| Area | Total painted area | Amount (rounded up) |
|---|---|---|
| 20 m² | 40 m² | about 5 L |
| 40 m² | 80 m² | about 9 L |
| 60 m² | 120 m² | about 13 L |
| 80 m² | 160 m² | about 17 L |
| 100 m² | 200 m² | about 21 L |
For new drywall or walls with a big color change, estimate primer (undercoat) separately. Area calculation and the waste rate concept are covered in the guide to estimating interior material quantities.
Frequently Asked Questions (FAQ)
How much area does 1 liter of paint cover?
This calculator uses a default of about 10 m² per liter for one coat of water-based paint. Depending on the product and surface this is usually 8-12 m²/L, and rough or absorbent surfaces lower the coverage so more paint is needed. Enter the coverage rate from the product spec sheet for a more accurate result.
How many coats of paint do I need?
Two coats are generally recommended. A single coat tends to leave streaks and show-through. Painting a dark color over white or making a big color change may need three coats, which increases the paint needed accordingly.
Why add a waste rate?
Paint absorbed by brushes and rollers, left in the tray, and lost to drips means you actually use more than the raw calculation. This calculator adds a default 5% waste rate. Beginners or complex wall shapes should raise it to about 10% to be safe.
Does this include primer (undercoat)?
This calculator only counts the topcoat (finish paint). New drywall or walls with a big color difference should get a separate coat of primer, which you can estimate again using 1 coat and that product's coverage rate.
Can I buy directly based on this result?
The result is a reference estimate. Paint is usually sold in fixed sizes such as 1 L, 4 L, and 18 L, so buy a size that covers the calculated liters with a little extra. Custom-tinted paint can vary slightly between batches, so it is best to buy plenty up front.
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Last updated: 2026-06-25