EstimatorKitBoard a room, and count the joints first
A room’s length, width and ceiling height are enough to hang it on paper: sheets for four walls and the ceiling, minus the openings, plus the screws, joint compound, tape and corner bead that go with them. Before it commits to a size it hangs the same room three times, in 8, 10 and 12 ft board, and shows what each length costs in butt joints — the square-end joints that have to be floated 24 in wide because there is no taper to hide them. A room whose walls are shorter than the board can have none at all.
- Walls and ceiling
- 3 board lengths compared
- Screws, mud, tape, bead
Wall to wall, floor to ceiling. An odd-shaped room is easier to add up in the square footage calculator first and enter as an equivalent rectangle.
1.6 lb a square foot — a working figure for 1/2 in regular board, not a published standard; the maker's data sheet has the real weight.
Longer board means fewer joints and heavier lifts. Both are shown below before you pick.
Half is the takeoff compromise: the strip above a door usually goes back above that door, the piece cut out of a window rarely goes anywhere.
Adjust the fastening and finishing rates
Board for 559 sq ft of wall and ceiling
18 × 48 in × 12 ft
- Hung, before the allowance
- 16
- Allowance
- +10%
- Screws
- 1 × 5 lb (1.8 lb)
- Joint compound
- 2 × 4.5 gal (63 lb)
- Joint tape
- 1 × 250 ft
- One sheet weighs
- 77 lb
| Length | Sheets | Butt joints | Lift |
|---|---|---|---|
| 8 ft | 22 | 11 (44 lf) | 51 lb |
| 10 ft | 22 | 11 (44 lf) | 64 lb |
| 12 ft | 16 | 4 (16 lf) | 77 lb |
Why that length
12 ft board leaves 4 butt joints, the fewest any stocked length manages on this room. At 12 ft you are hanging 4 butt joints over 16 linear feet, against 88 feet of tapered joint. Each butt foot is floated about 24 in wide to hide the bump; each tapered foot is filled in a 10 in band and forgets about it.
A 48 in × 12 ft sheet of 1/2 in regular is 77 lb. That is the trade-off nobody writes down: the length that finishes fastest is the one two people have to get round a stairwell.
Tape is counted off the joints rather than off the sheets: 88 lf of tapered joint, 16 lf of butt, 52 lf of wall-to-ceiling angle and 32 lf of vertical corner — 188 lf in all, which works out at 10.4 ft a sheet on this room. Outside corners are not in that figure; they take bead.
Screw count uses 320 to the pound — a working figure for #6 × 1 1/4 in coarse-thread drywall screws rather than a published one, and it varies with length and thread — longer screws for 5/8 in board run fewer to the pound — and the count printed on the box beats it. Compound boxes use 61.7 lb — the net weight printed on a 4.5 gallon box of ready-mixed all-purpose joint compound. Tape rolls use 250 ft — a standard roll of paper joint tape.
Net board area divided by one sheet gives 12, which is the floor rather than the order — it assumes every offcut lands on another wall at the same height.
Sheet coverage, for checking against a quote: 4 × 8 is 32 sq ft, 4 × 10 is 40, 4 × 12 is 48. At 54 in wide each of those goes up by an eighth.
The joint that decides how long a room takes
A drywall takeoff is two surfaces and a subtraction. Walls are the perimeter times the ceiling height, the ceiling is the footprint, and the openings come off — except that the subtraction is the part estimators argue about, because board removed from a wall is not board saved. The piece cut out above a door is the piece that goes back above that door; the piece cut out of a window opening usually is not, because it comes out of the middle of a sheet in two directions. So an opening only changes the order once the deduction reaches the coverage of one whole board, which for a 4 × 12 is 48 sq ft — more than two doors’ worth. That is why this page takes half by default and shows the sheet count without moving until the deduction earns it. Rooms that are not rectangles are easier added up as pieces first in the square footage calculator and entered here as the equivalent box.
The decision that actually costs money is made at the rack, and almost nobody makes it deliberately. Sheets arrive with their long edges recessed at the factory, so where two long edges meet the tape sits in a shallow trough and three coats bring it back flush in a 10 in band. Where two square-cut ends meet there is no trough, the tape stands proud, and the only way to hide it is to crown the joint — feather compound out about two feet each side so the wall reads as a very slight rise instead of a ridge. Buy board that spans the wall and those joints do not exist: a 12 ft room hung in 12 ft sheets has none, while the same room in 8 ft board picks up one in every course of every wall. Hanging the sheets flat rather than upright is the same argument in the other direction, since laid horizontally the long tapered edges do the work and there is around a quarter less joint in the room. The counterweight is what a long sheet weighs: 48 sq ft of 5/8 in Type X is about 106 lb at this page’s working weight, and no joint schedule is worth dropping a board down a stairwell for.
Finishing quantities follow from that schedule rather than from the area. Screws and compound scale with sheets — the defaults are about 32 and 3.5 lb each, working figures rather than published ones — and both are worth adjusting, because a ceiling screwed tighter at the edges runs above the first figure and a level 5 skim coat, which is a fourth coat applied to the whole surface rather than to the joints, runs above the second. Tape does not scale with sheets at all: it is the tapered feet plus the butt feet plus the perimeter where walls meet ceiling plus the four vertical corners, and in a small room those last two are most of it. Corner bead is counted differently again, one uncut stick per outside corner, because a bead spliced part way up a chase cracks along the splice within a year. Once the walls are closed, what happens next is somebody else’s arithmetic — the flooring calculator for what goes down afterwards — and what is behind them, the structural panel on the other face of the same studs, is counted in courses on the plywood calculator.
Before you order the board
How many sheets of drywall do I need for a 12 by 14 ft room?
Sixteen sheets of 4 × 12 with the ceiling boarded, against twenty-two of 4 × 8 — and the reason to care is that the 12 ft board leaves four butt joints where the 8 ft board leaves eleven. The room is 584 sq ft gross across walls and ceiling, so a plain division asks for thirteen 4 × 12 sheets or nineteen 4 × 8 — under the laid-out count both times, because a wall 2 ft longer than the board still needs a second sheet in every course of it. A door and two windows take about 25 sq ft off at the half setting, which is not a whole sheet in either size and so changes nothing.
Should drywall be hung horizontally or vertically?
Horizontally in a house, vertically in most commercial work, and the reason is the tapered edge. Laid flat, the long tapered edges of two sheets meet in one continuous horizontal line at about 4 ft, which is a comfortable working height, and there is roughly a quarter less joint to finish than standing the same sheets up. Vertical hanging exists because metal-stud partitions with fire ratings are tested that way and because a wall taller than the board is going to have a horizontal joint regardless. On a 9 ft wall, three courses of 48 in board means two horizontal joints and a 1 ft rip along the top, where two courses of 54 in board means one joint and no rip — which is the argument the width setting on this page exists to make.
Do you subtract doors and windows from a drywall estimate?
Only when they add up to a whole sheet, because the board around an opening comes out of sheets you have already bought. A 3 by 7 door is 21 sq ft, two thirds of a 4 × 8 sheet, and the strip cut out above it is exactly the piece that goes back above that same door — so nothing is saved and nothing is wasted. Deduct it in full and the order comes up a sheet short on a room with several openings; deduct nothing and a wall of glass is paid for twice. The half setting is the working compromise, and the sheet count only moves once the deduction crosses the coverage of one board.
Is 1/2 in or 5/8 in board right for this room?
Half inch on the walls and five eighths on the ceiling is the usual split, and the ceiling half of it is not a preference. Half-inch board on framing at 24 in on center sags between the joists, and GA-216 does not permit it there under a water-based texture — the fixes are 5/8 in, board sold specifically as sag-resistant ceiling board, or strapping the ceiling down to 16 in first. Five eighths Type X is also what the IRC asks for on a garage ceiling with living space above it. The cost is weight: at the working weights this page uses — the maker's data sheet has the real ones — a 4 × 12 sheet of 5/8 in is about 106 lb against 77 lb in half inch, which is the difference between two people and three.