drywall cost estimate

Figuring a drywall cost estimate is a bit time consuming but not impossible. Approaching it systematically is your best bet. I will cover four different square footage totals: Ceiling, exterior walls, interior walls, bathroom walls. The numbers I’m using are based on a single level home measuring 30’x 40’ with 8’ ceilings.


The square footage of a 30 x 40 home is 1,200 sq. feet. That is also an excellent average to use for the square footage of the ceiling.

1,200 sq. feet of ceiling


Take the basic exterior walls of the example home 30’x40’ even though the interior measurements are smaller, it wont hurt to have extra trim pieces. 30+30+40+40= 140 linear feet. Multiply 140 by the height of 8ft.

1,120 sq. feet for exterior walls.


Consider that your interior walls will have sheet-rock on both sides, so only one linear foot measurement of each wall is necessary, and times it by two. 65’ x 2 = 130’ linear feet. Now multiply that by the wall height of 8 feet. 130 x 8= 1,040

1,040 sq. feet interior walls.


The 1,040 sq. feet number above includes the bathroom interior walls, however, bathrooms need special sheet-rock that is water resistant called green-board. Use the same process of HxW to get your bathroom wall square footage. For example purposes we'll say there is 256 sq. feet.


Drywall boards are either 4'x8' or 4'x12'. Usually ceilings are 4'x12' because of the large uninterrupted spans resulting in less seams. The larger boards are heavier and need extra help hanging.

To figure how many sheet-rock boards you’ll need to buy, add the total square feet and divide by either 32 or 48. For our example home, we will use all 4'x8' boards on walls and ceilings.

3,360 total square footage

Now subtract out the bathroom measurement of 256 sq. feet of green-board and the total square footage is 3,104.

3,104 / 32 = 97 (4'x8' regular boards)

256 / 32 = 8 (4'x8' green-boards)

105 boards in total

Call your local dealer and get prices and do the multiplication plus sales tax.


Figure how much tape you’ll need by multiplying the number of 4x8 boards you need by 24.
105 boards x 24= 2,520 linear feet. Now divide that number by 250 or 500 (common sizes of drywall tape rolls)

2,520 / 250 = 10.08 rolls


Divide the total square footage by 400 to figure how many buckets of ready mix joint compound you’ll need. 3,360 / 400 = 9 buckets


To figure how many pounds of screws you’ll need, divide total square footage by 300.

3,360 / 300 = 11.2lbs of 1-1/4 inch drywall screws.

Corner bead is made in 8 or 10 foot sections. Count your corners and determine how many sections you’ll need.

Coming up with a good drywall-cost-estimate doesn't require a professional, just a calculator and a quiet space.

Shop around for the best prices on drywall tools, supplies and boards. You’ll be amazed that not all stores are equal and it could save you money, which is the whole idea.

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