Quick Room Paint Calculator
Calculate paint needed from room dimensions with door and window offsets.
Returns gallons and liters based on standard 400 sq ft per gallon wall coverage rate.
Paint Needed
Room paint estimation calculates total wall area and divides by paint coverage.
Wall Area = 2 × (Length + Width) × Height
This gives the total area of all four walls (no ceiling).
Coverage per unit:
- Gallons: ~350 sq ft per gallon (one coat)
- Liters: ~10 sq m per liter (one coat)
Unit support:
- Input in feet or meters
- Output in gallons or liters
Tips:
- Most rooms need 2 coats — the calculator shows both
- Subtract ~20 sq ft per standard door and ~15 sq ft per window if you want precision
- Dark-to-light color changes may need a primer coat first