Drywall calculator

Sheets, screws, tape and compound for the board you are hanging.

I know my
Units
Sheet size
Joint compound

Floor to ceiling. Walls are the perimeter times this.

Ceiling

Counted at 20 ft² each.

Counted at 15 ft² each.

Why 10%?

Ten percent covers the offcuts that come from working round openings and finishing runs. Rooms with many doors, windows and short walls generate more waste than a long unbroken wall, because every cut leaves a piece too small to hang anywhere else.

Add a price

Board is priced per sheet and varies by thickness and type.

Enter your wall and ceiling areas to get a sheet count.

    What a drywall calculator ends in

    Board is bought by the sheet, so every calculation ends in a whole number of sheets and nothing smaller. Walls and ceilings are added together because they are hung from the same stack, then an allowance is added for offcuts, then the total is divided by whatever sheet size you have chosen to carry up the stairs.

    Sheets = (wall area + ceiling area) × 1.10 ÷ sheet area Screws = wall area × (28–32 ÷ 32) + ceiling area × (36–40 ÷ 32) Tape ≈ board area × 350 ÷ 1000, in linear feet Compound ≈ board area × rate ÷ 1000, in pounds
    • sheet area — 32 sq ft for 4 × 8, 40 for 4 × 10, 48 for 4 × 12
    • 1.10 — the ten percent offcut allowance
    • board area — what you actually hang, not the sheets you carry home
    • 28–32 and 36–40 — screws per 4 × 8 sheet at 16 in centres on walls and 12 in on ceilings
    • rate — 123–140 lb per 1,000 sq ft for conventional all-purpose compound, about 72 for a lightweight

    Worked example: 800 sq ft of wall and 200 of ceiling

    Board = 800 + 200 = 1,000 sq ft With 10% = 1,100 sq ft 4 × 8 = 1,100 ÷ 32 = 35 sheets 4 × 12 = 1,100 ÷ 48 = 23 sheets Screws = 800 × 0.875–1.0 + 200 × 1.125–1.25 = 925–1,050 Tape ≈ 350 linear feet Compound ≈ 123–140 lb conventional, or 72–80 lb lightweight

    Twelve fewer sheets in the larger size, and twelve fewer sheets means fewer butt joints to hide. That is the real argument for long board, and the reason to check your stairwell before ordering it.

    Why fastener spacing is not this calculator's decision

    The screw figures here are estimating rates taken from manufacturer guidance, useful for filling a trolley. They are not a specification. Actual spacing is fixed by your local building code and by the board manufacturer's own schedule, and it changes with framing centres, board thickness, whether the assembly is fire or shear rated, and whether you are screwing to timber or steel. Look it up for your job. A calculator that told you otherwise would be overstepping.

    Common mistakes

    • Forgetting the ceiling. On a 12 by 16 room the ceiling is 192 sq ft, roughly six extra sheets, and it is the hardest part to go back for.
    • Deducting every opening. Board is hung over openings and cut out afterwards. Deducting a door you then cut round leaves you a sheet short.
    • Buying the sheet size you can lift rather than the one that fits. Two people and a panel lift beat a day of extra taping.
    • Under-ordering compound. A three-coat finish uses far more than people expect, and running out mid-coat leaves a visible ridge where the wet edge dried.

    When these numbers do not apply

    • Level 5 finishes. A skim coat across the whole surface uses substantially more compound than the three-coat figure here.
    • Steel framing. Different screws, different spacing, and the counts shift accordingly.
    • Fire and acoustic assemblies. Double-layer board doubles the sheets and changes the fastener schedule entirely.
    • Curved and vaulted work. Flexible board comes in smaller sheets and wastes far more than a flat ceiling.

    After the board goes up

    Once the compound is sanded, the paint calculator works out gallons including the primer coat new board always needs. If the plan is panelling rather than plain paint, the board and batten calculator spaces the battens so every bay comes out equal.

    Sheets and tape by wall area

    Wall area4 × 84 × 104 × 12Joint tape (ft)
    400 ft²141110140
    800 ft²282219280
    1000 ft²352823350
    1600 ft²554437560
    2400 ft²836655840

    Sheets include the standard 10% waste; tape is calculated on the area actually installed, because you do not tape the offcuts.

    Elevation of a 52 by 8 foot wall divided into thirteen 4 foot drywall sheets.
    Drawn to scale.

    Common questions

    Can I just give it the room size?

    Yes, and that is what it asks for first. The paint calculator has always taken a length, a width and a height; these three asked for a wall area in square feet, for the same room on the same job — so anyone doing both did the multiplication themselves for one of them. Enter the room and it works out the walls as the perimeter times the height. Boarding the ceiling is a separate choice rather than an assumption: plenty of rooms are done to the walls only, and assuming otherwise over-orders by about a fifth. The square footage route is still there for anyone who has an area already.

    How many sheets of drywall do I need?

    Add wall and ceiling areas, add ten percent, then divide by your sheet size. A thousand square feet of board comes to 35 sheets at 4 × 8 or 23 at 4 × 12.

    Which sheet size should I buy?

    The longest that will physically reach the room. Long board means fewer butt joints, and butt joints are the ones that show. Weight and stairwells are what usually decide it instead.

    How accurate are the screw and compound figures?

    They are approximate, and labelled as such. They shift with framing centres, board thickness, finish level and how much you waste. Treat them as a shopping guide, not a specification.

    Should I subtract doors and windows?

    Usually not, which is why the door and window fields start blank. Standard practice is to hang the board straight over a small opening and cut it out afterwards — it gives a cleaner joint line, and the cut-out piece is rarely big enough to use anywhere else. Fill the fields in only if you are cutting to fit, or if the openings are large enough that hanging over them would genuinely waste sheets: a wide patio door, a run of full-height glazing.

    How much does each opening take off?

    Twenty square feet for a door and fifteen for a window — the same standard openings the paint calculator uses, taken from the same place so the two can never drift apart. They come off the wall area only, because a door is not in the ceiling. Screws, tape and compound follow the deducted figure too: you do not tape the hole where the door goes.

    How much compound is in a bucket?

    A lightweight all-purpose is commonly a 4.5 gallon pail at about 36 lb, so 1,000 sq ft of board takes two. Conventional all-purpose is heavier for the same coverage, which is why the compound type is a choice here rather than a fixed rate. Setting compounds come as dry powder and cover differently again, so check the pail.

    Sources

    Default waste allowance
    10%

    The 10% allowance is the 1.10 multiplier given in the drywall formula. Screw, tape and compound rates are trade estimating conventions rather than physical constants: they vary with sheet size, framing spacing, finish level and waste, and are always presented as approximate. Fastener spacing is governed by local code and the manufacturer's schedule. Screw counts are ranges because spacing within a schedule is not fixed, and joint compound is split by product type because the two differ by roughly 2x — a lightweight compound covering the same board at about 72 lb per 1,000 ft2 against 123 to 140 for conventional all-purpose. The lightweight figure is now verified against USG's own submittal sheet, and it was wrong: USG publishes 9 to 10 gallons per 1,000 sq ft, which at 4.5 gal and 36 lb per pail is 72 to 80 lb — not the flat 72 stored here, which was the bottom of the band quoted as if it were the whole of it. Coverage is published in gallons rather than pounds, so the gallon figures are stored alongside and are the ones to trust.

    Unit conversions are exact by definition and need no source.

    How we choose and cite these figures

    By Team MaterialMath. Published . Last checked . How these figures are sourced and checked.

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