DIY Quantity Calc

Paint calculator for a room

Gallons of paint for the walls of a room. Change the numbers and the answer updates; the starting values are only an example.

14 ft12 ft8 ft
Measurements
Adjust to your doors.
Adjust to your windows.
Read it from the can; paints differ.

Shopping list

Wall area416sq ft
Paintable area366sq ft
Paint needed2.09gallons
Buy, rounded up to a quarter2.25gallons

How it is worked out

  1. Wall area is the room's perimeter, 2 times length plus width, times the wall height.
  2. Doors and windows are subtracted using the areas you enter.
  3. Gallons are the paintable area times the coats divided by the coverage on the can.

Worked example

With the starting values, a room 14 ft by 12 ft with 8 ft walls has 416 square feet of wall, 366 square feet after 1 door and 2 windows, and needs 2.09 gallons for 2 coats at 350 square feet per gallon, so buy 2.25 gallons.

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