Drywall Planner

What it is

Drywall Planner is a free online calculator designed for DIY users and trade professionals planning drywall projects. Users enter room dimensions, wall height, and opening information; the calculator returns the number of sheets needed, joint compound in pounds and pails, joint tape in linear feet and rolls, and drywall screws, with a standard 10% waste allowance included by default. The calculator accounts for standard door and window openings, performs sheet layouts wall by wall the way a hanger would, and works entirely in the browser with no sign-up required. An optional cost estimate feature lets users enter their local price per sheet and labor rates. The tool supports both imperial and metric measurements and includes guides explaining the formulas and estimating rules of thumb behind every calculation.

Questions from the bench

How many drywall sheets do I need for a 12x12 room?

For a 12 by 12 foot room with 8 foot ceilings, one door and one window on the walls only, buy 14 sheets of 4x8 board. The walls are 384 sq ft gross, 348 sq ft net after deducting openings, and they take 12 sheets laid out with 2 spares. If you include the ceiling as well, add the 144 sq ft ceiling area for a total of 17 sheets laid out and 19 with spares.

Does the calculator include a waste factor?

Yes. The calculator adds 10% by default, which is the standard allowance for cuts and offcuts in a rectangular room. You can adjust the waste percentage in the calculator, and 15% is recommended for rooms with many angles, closets or stairwells where offcuts are harder to reuse.

How much does a sheet of drywall cost?

According to Fixr's cost guide updated January 31, 2025, a standard 4x8 sheet costs $10 to $15 for material only. The actual price depends on your region, the thickness of the board, whether it is standard or specialty board like moisture resistant or fire rated, and prices fluctuate frequently. The calculator asks you to enter your own local price per sheet rather than using a national average.

Should I subtract doors and windows from drywall square footage?

Yes, for any opening that is door-sized or larger. The calculator uses standard deductions of 21 sq ft per door (equivalent to a 3 by 7 foot opening), 15 sq ft per window (equivalent to a 3 by 5 foot opening), and 112 sq ft per garage door (16 by 7 feet). For custom openings like patio sliders or pass-throughs, you can enter the width and height. Small openings like outlets and vents should be left in since cutting around them is what the waste factor is designed to cover.

Can I use this drywall calculator in metric?

Yes. You can switch the unit toggle to metric and enter your measurements in meters and centimeters. Your existing measurements are automatically converted, and the results display total area in both square feet and square meters, though sheet sizes remain in the imperial sizes sold in North America.