| Room | Length (m) | Width (m) | Height (m) | Doors | Door area (m²) | Windows | Window area (m²) | Include ceiling | Remove |
|---|
Defaults: door area 2.0 m² (21 ft²), window area 1.2 m² (12 ft²). Openings reduce wall area only.
Results
| Room | Wall area | Ceiling area | Openings | Paintable area |
|---|
Can size suggestions
Unit & coverage notes
- Metric default coverage: 10 m² per liter.
- Imperial default coverage: 350 ft² per gallon.
- Adjust coverage to match product data sheets.
Example data
| Room | Length | Width | Height | Doors | Door area | Windows | Window area | Include ceiling |
|---|---|---|---|---|---|---|---|---|
| Bedroom | 4.2 m | 3.6 m | 2.7 m | 1 | 2.0 m² | 2 | 1.2 m² | Yes |
| Hall | 5.0 m | 2.8 m | 2.7 m | 1 | 2.0 m² | 1 | 1.2 m² | No |
Use the “Add room” button to input similar values, then press “Calculate”.
Formula used
Wall area = 2 × (Length + Width) × Height
Ceiling area (optional) = Length × Width
Openings area = Doors × DoorArea + Windows × WindowArea
Paintable area = max(0, Wall area − Openings area) + Ceiling area (if included)
Adjusted area = Paintable area × Coats × (1 + Wastage%)
Liters needed = Adjusted area (m²) / Coverage (m²/L)
Gallons needed = Adjusted area (ft²) / Coverage (ft²/gal)
Conversions: 1 m = 3.28084 ft; 1 m² = 10.7639 ft²; 1 gal (US) = 3.78541 L.
How to use this calculator
- Select your preferred units and verify coverage.
- Enter each room’s length, width, and height.
- Set counts and areas for doors and windows.
- Tick “Include ceiling” to paint ceilings for that room.
- Choose coats and a reasonable wastage percentage.
- Click “Calculate” to see paint amounts and areas.
- Export CSV or PDF to share, quote, or plan purchases.
FAQs
Typical interior coverage reference
| Finish | Coverage (m²/L) | Coverage (ft²/gal) | Notes |
|---|---|---|---|
| Flat / Matte | 10–12 | 350–400 | Good for ceilings, hides minor defects. |
| Eggshell / Satin | 8–10 | 300–350 | Walls in living areas and bedrooms. |
| Semi‑gloss | 6–8 | 250–300 | Trim, kitchens, bathrooms; more durable. |
Standard opening areas reference
| Opening | Approx. size | Area (m²) | Area (ft²) |
|---|---|---|---|
| Interior door | 0.9 × 2.0 m | 1.80 | 19.4 |
| Tall door | 0.9 × 2.1 m | 1.89 | 20.3 |
| Double door | 1.6 × 2.0 m | 3.20 | 34.4 |
| Standard window | 1.0 × 1.2 m | 1.20 | 12.9 |
| Sliding window | 1.2 × 1.5 m | 1.80 | 19.4 |
Use these as starting points; measure actual openings on site for accuracy.
Can coverage at current settings
Computed per coat using your coverage field. Updates with unit or coverage changes.
Metric cans
| Size (L) | Area (m²) | Area (ft²) |
|---|
Imperial cans
| Size (gal) | Area (ft²) | Area (m²) |
|---|