How to Calculate Drywall Cost — Step by Step

The six steps at a glance

A drywall job costs four things, not one: the sheets, the supplies, the labour and the waste. The sheets are the boards themselves, priced by the billable wall area. The supplies are the mud, the tape and the screws that finish the joints. The labour is the hanging and the finishing, priced by the net wall area. The six steps are: measure the length and the width, measure the ceiling height, work out the gross and net wall area, add the waste and count the sheets, price the sheets, the supplies and the labour, and add it all up. The worked example is a 12 by 10 ft room with an 8 ft ceiling, 1 door and 2 windows, sheets at $15.00 and labour at $1.50 a square foot, and it comes to $721.85, or $2.40 a square foot.

Step 1 — Measure the length and the width

Measure the length of the room in feet, from wall to wall, and the width the same way. A typical bedroom is about 12 by 10 ft, and that is the size the worked example uses. Measure at the floor, where the boards start, and write both numbers down. If the room is not a rectangle, split it into rectangles and work out each one on its own: a 12 by 10 ft room with a 4 by 4 ft alcove is two rooms for pricing, and one rectangle understates the wall area.

Step 2 — Measure the ceiling height

Measure the ceiling height in feet, from the floor to the ceiling. About 8 ft is typical, and 9 ft is typical for a newer house. The worked example uses 8 ft. The height matters because the wall area is the length of the walls times the height: a 12 by 10 ft room with a 9 ft ceiling has 345 square feet of net wall, against 301 with an 8 ft ceiling, and the total rises from $721.85 to $818.25. Measure in the middle of the room if the ceiling slopes.

Step 3 — Work out the gross and net wall area

The gross wall area is 2 times the length plus the width, times the ceiling height: the two long walls and the two short walls. For the worked example, 2 times 12 plus 10, times 8, is 352 square feet. Then take the openings off: one door is 3 by 7 ft, or 21 square feet, and one window is 3 by 5 ft, or 15 square feet. For the worked example, 1 door and 2 windows take off 51 square feet, so the net area is 352 minus 51, which is 301 square feet. Measure twice: an area that is wrong by 10 percent makes the price wrong by 10 percent too.

Step 4 — Add the waste and count the sheets

The billable area is the net area times 1 plus the waste: for the worked example, 301 times 1.10 is 331.10 square feet. The waste is the offcuts and the damaged boards, and about 10 percent is typical for a rectangular room. The sheets are the billable area divided by 32, rounded up, because one 4 by 8 ft sheet covers 32 square feet. For the worked example, 331.10 divided by 32 is 10.35, rounded up to 11 sheets. Always round up: you cannot buy a third of a sheet. With 0 percent waste the billable is 301 square feet, which is 10 sheets, but it leaves no board for a miscut.

Step 5 — Price the sheets, the supplies and the labour

The sheet cost is the sheets times the sheet price: for the worked example, 11 times $15.00 is $165.00. The supplies are $0.35 times the net area, for the mud, the tape and the screws: $0.35 times 301 is $105.35. The labour is the labour rate times the net area: $1.50 times 301 is $451.50. The labour is most of the job, and it is the part that changes the most between quotes, so get the rate in writing before you compare them. If you do the labour yourself, enter $0, and the total falls to $270.35.

Step 6 — Add it up, and work out the cost per square foot

Add the sheet cost, the supplies and the labour together: for the worked example, $165.00 plus $105.35 plus $451.50 is $721.85. That is the total drywall cost. To work out the cost per square foot, divide the total by the net area: $721.85 divided by 301 is $2.40 a square foot. Use the per-square-foot figure to compare quotes: two contractors can quote different totals for the same room. A $1,000 budget covers 422.72 square feet of net wall, and a $500 budget covers 211.36 square feet.

The worked example, line by line

Setup: 12 by 10 ft, 8 ft ceiling, 1 door, 2 windows, sheet $15.00, labour $1.50 a square foot, waste 10 percent, budget $1,000. Line 1, the gross wall area: 2 times 12 plus 10, times 8, is 352.00 square feet. Line 2, the openings and the net area: 1 door times 21 plus 2 windows times 15 is 51.00 square feet, so the net is 352 minus 51, which is 301.00 square feet. Line 3, the billable area and the sheets: 301 times 1.10 is 331.10 square feet, and 331.10 divided by 32 is 10.35, rounded up to 11 sheets. Line 4, the costs: 11 times $15.00 is $165.00, $0.35 times 301 is $105.35, and $1.50 times 301 is $451.50. Line 5, the total: $165.00 plus $105.35 plus $451.50 is $721.85, or $2.40 a square foot. Line 6, the budget: $1,000 covers 422.72 square feet of net wall, and $500 covers 211.36. Every figure here comes from the same six steps, and the drywall cost calculator runs them for any room you enter.

Other rooms, checked

A 15 by 12 ft room is 381.00 square feet of net wall, the billable is 419.10 square feet, and the sheets are 14. The sheet cost is $210.00, the supplies are $133.35, the labour is $571.50, and the total is $914.85, or $2.40 a square foot. A 12 by 10 ft room with a 9 ft ceiling is 345.00 square feet of net wall, the billable is 379.50 square feet, and the room needs 12 sheets. The total is $818.25, or $2.37 a square foot. At $20.00 a sheet the room costs $776.85, with DIY labour at $0 it costs $270.35, and with 0 percent waste it costs $706.85 with 10 sheets.

What the six steps leave out

The six steps price the walls themselves, and they leave out the ceiling, the primer and the paint, the trim, and tax. Ask the contractor whether the quote includes those. A room with a curved wall, a sloped ceiling, or a lot of corners costs more than the six steps say, because the drywall is cut to fit and the waste is higher. A bigger door or window takes more off the wall area than the standard 21 and 15 square feet, so measure the openings if they are not standard. For the sheet sizes, see the drywall sizes chart, and for the paint, see the paint cost calculator.

Room	Net area	Billable	Sheets	Total	Per sq ft
12 x 10 ft, 8 ft ceiling (worked example)	301.00 sq ft	331.10 sq ft	11	$721.85	$2.40
15 x 12 ft, 8 ft ceiling	381.00 sq ft	419.10 sq ft	14	$914.85	$2.40
12 x 10 ft, 9 ft ceiling	345.00 sq ft	379.50 sq ft	12	$818.25	$2.37
12 x 10 ft, sheet $20.00	301.00 sq ft	331.10 sq ft	11	$776.85	$2.58
12 x 10 ft, DIY labour $0	301.00 sq ft	331.10 sq ft	11	$270.35	$0.90
12 x 10 ft, waste 0%	301.00 sq ft	301.00 sq ft	10	$706.85	$2.35