Drywall Calculator
Work out how many sheets of drywall a room takes, plus the joint compound, tape, screws and corner bead that go with them — with a printable shopping list, a cost estimate and an honest time figure.
What are you covering?
How to use this calculator
1. Measure the surfaces
Give the room's length, width and ceiling height and the calculator works out 2 × (length + width) × height for the walls, adding length × width again if the ceiling is getting board. Odd-shaped rooms, stairwells and soffits are easier to handle by switching the dropdown to "Surface area I already measured" and typing one total.
2. Deduct the openings
Count the doorways and windows and check the default areas — 21 sq ft for a 3 × 7 door, 15 sq ft for a 3 × 5 window. Both figures are editable, so a patio slider or a garage door can be entered as its real size instead.
3. Pick a sheet size and a waste allowance
Sheets are counted as ceiling(net area × (1 + waste) ÷ sheet area). The waste percentage covers offcuts you cannot reuse; 10% suits a plain rectangular room and 15% is safer once you add closets, angles and a lot of short walls.
4. Adjust the prices, then print the list
Every unit price is editable, so put in what your store actually charges. The shopping list tab downloads as CSV or prints on one page — handy at the contractor desk where the sheets get pulled from the rack.
Drywall FAQs
How many sheets of drywall do I need?
Add up every surface you are covering, subtract the door and window openings, add a waste allowance, then divide by the area of one sheet and round up. A 4 × 8 sheet is 32 sq ft, a 4 × 10 is 40 sq ft and a 4 × 12 is 48 sq ft. A 12 × 12 ft bedroom with 8 ft ceilings, one door and one window works out to 492 sq ft net, 541 sq ft with 10% waste, and 17 sheets of 4 × 8.
How much joint compound and tape will I use?
Budget about 0.053 lb of ready-mixed compound per square foot of board for a three-coat finish, which is roughly one 4.5 gallon (61.7 lb) bucket per 1,150 sq ft. For tape, the rule used on this page is 1 linear foot of tape per 2 sq ft of board — a figure that comes from the seams a 4 ft wide sheet creates — so a 500 ft roll covers about 1,000 sq ft. Buy the bucket and the roll whole; neither keeps well once opened, but running out mid-coat is worse.
How many drywall screws do I need?
One screw per square foot is the standard planning figure, which lands near 32 screws on a 4 × 8 sheet hung on 16 in centers. A pound of 1-1/4 in coarse-thread screws holds roughly 320 of them, so one pound covers about 320 sq ft. Ceilings get screwed tighter than walls, so round the box count up rather than down.
Should I subtract doors and windows?
Subtract them from the area you have to tape and mud, but do not expect the full saving in sheets. Board gets cut around openings and the offcuts are often too small to reuse, which is exactly what the waste percentage exists to absorb. If the openings are small, leaving them in gives a slightly conservative sheet count — never a bad thing on a Saturday morning.
Should I buy 4 × 8, 4 × 10 or 4 × 12 sheets?
Longer boards mean fewer butt joints, which are the seams that are hardest to hide, so crews reach for 4 × 12 wherever the room and the stairwell allow it. The trade-off is handling: half-inch board runs about 1.6 lb per square foot, so a 4 × 8 sheet is roughly 51 lb and a 4 × 12 is about 77 lb — a genuine two-person lift. The compare panel above puts both options side by side for your room.
How long does hanging and finishing drywall take?
The estimate here allows 15 minutes per sheet to hang and 0.9 minutes per square foot to tape, coat three times and sand. Double it if this is your first room. The bigger constraint is drying: each coat of compound wants overnight, so even a small bedroom is a three or four day project no matter how few hands-on hours it adds up to.
What do I do after the drywall is up?
Prime the new board before painting — bare paper and dried compound drink up finish coats at very different rates, and skipping primer leaves the seams visible in raking light. Size the primer and paint with the paint calculator, and once the dust has settled, work out the room's floors with the flooring calculator.