Paint Calculator
Find out how many gallons of paint you need for any room.
Calculate how many gallons or liters of interior or exterior paint you need from a known wall area or from room dimensions, coats, and deductions for doors and windows.
Measurement System
Your Estimate
Calculated Wall & Ceiling Area
512 ft²
Net Paintable Area
425 ft²
Gallons Needed
2.43 gal
Gallon Cans (rounded up)
3
Assumes 350 sq ft coverage per gallon. Check your paint can label for exact coverage.
Results Actions
Accuracy & Assumptions
- Results are estimates only.
- Paint coverage per gallon varies by brand, sheen and surface texture.
- Dimension mode assumes a rectangular room and calculates wall area as 2 × (length + width) × height.
- Ceiling area equals room length × room width when included.
- Consider buying an additional 5–10% extra paint for touch-ups and future repairs.
- Verify wall, ceiling and trim measurements before purchasing paint.
- Check the manufacturer's coverage rate and recommended coat count on the product label.
How This Calculator Works
- 1Choose whether to enter a known wall area or calculate wall area from room length, width and height.
- 2When calculating from dimensions, optionally include the ceiling area.
- 3Choose Imperial or Metric measurements and enter how many coats you plan to apply.
- 4Add the number of doors and windows so we can deduct unpainted area.
- 5We divide net paintable area by 350 sq ft per gallon or 10 m² per liter.
Helpful Tips
- Check the coverage rate printed on your specific paint can — it varies by brand and finish.
- Dark color changes and bare drywall usually need an extra coat or a tinted primer.
- Buy from the same batch/lot number to avoid subtle color variation between cans.
This calculator provides an estimate for planning purposes only. Material needs vary by site conditions, waste and supplier specifications — always confirm final quantities with your contractor or supplier before purchasing.