Free · Home and garden calculators 🏡

Room Wall Paint Coverage & Cost Calculator

Estimate paint volume and cost from room dimensions, openings, coats and product coverage.

  • Formula & worked example
  • Private in your browser
  • No signup
Go to tool

Calculator inputs

Loading calculator…

How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Edit a calculated value to solve backwards, or lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A 5 × 4 meter room with 3 meter walls has 54 m² of wall area. Subtract a 2 m² door and two 1 m² windows to get 50 m². Two coats at 10 m² per liter need 10 liters, costing 120 at 12 per liter.

Wall area = 2 × (length + width) × height; paint volume = (wall area − openings) × coats ÷ coverage; cost = volume × unit price

Worked example

Enter these known values and leave the other values blank.

Room length
5 m
Room width
4 m
Room height
3 m
Number of doors
1
Door height
200 cm
Door width
100 cm
Number of windows
2
Window height
100 cm
Window width
100 cm
Desired number of coats
2
Paint efficiency
10 m² / L
Cost per unit volume
12 USD / L
Room wall area
54 m²
Total door area
2 m²
Total window area
2 m²
Total area to be painted
50 m²
Volume of paint needed
10 L
Total cost
120 USD

Assumptions and limitations

  • Coverage is the usable area per unit volume for one coat. Absorbent or rough surfaces may need more paint.
  • Enter actual opening sizes, consistent price units and the intended number of coats.

Common questions

Does the estimate include the ceiling and whole paint cans?

It covers the four walls of a rectangular room and subtracts the entered openings. The ceiling, primer, spills and extra reserve are excluded. Round the calculated volume up to available can sizes after checking the product coverage for your surface.

References

The geometry and coverage model follow the referenced definition. Bookify uses the exact US gallon for volume, coverage and price conversions.

Explore home and garden calculators 🏡 or browse all construction calculators.