Formula Reference
Wall LF is one face
Gross area is wall length times height, which is a single side of the partition. A partition boarded both faces is twice that. Do not simply double the wall length if framing is switched on, or you will buy studs for a wall that does not exist: keep the length actual on the framed line, and add a second product line for the far face with Include Framing off. Board, compound, tape and screws then double and the framing does not.
Joint compound
Level 4 is anchored to a published rate. USG's submittal sheet for Sheetrock Brand All Purpose Joint Compound gives coverage as approximately 10 gallons per 1,000 sq ft of gypsum panels — 0.010 gal/SF, or about 450 SF of board per 4.5-gallon pail. The midweight version of the same product is rated at 9.4 gallons per 1,000 sq ft, so the two agree to within six per cent.
That figure covers the complete job the product is sold for: embedding the tape, the fill coat and the finish coats, plus fasteners, bead and trim. It is the Level 4 factor here. Levels 1, 2 and 3 are scaled down from Level 4 in proportion to how much of that three-coat system each calls for — those proportions are this calculator's assumption, not a published number. If your own history says otherwise, your history wins.
Level 5 is built rather than scaled, because it is a different job: Level 4's taping plus a skim over the entire surface. USG's submittal sheet for Cover Coat Compound, the product sold for skimming, gives coverage as approximately 90–120 sq ft per 4.5-gallon pail at 1/16 inch. Scaled to a 1/64 inch skim that is 9.4–12.5 gallons per 1,000 sq ft, which on top of Level 4's ten puts the total near 19–23. The factor here is 0.021 gal/SF, the middle of that range. The 1/64 inch skim thickness is this tool's assumption — GA-214 specifies only “a thin skim coat” and gives no dimension, and a heavy hand will use appreciably more.
Joint tape
USG's submittal sheet for Sheetrock Brand Paper Joint Tape publishes approximately 370 ft per 1,000 sq ft of gypsum panels. Geometry arrives at the same answer from the other direction: in a grid of a × b panels, joint length per square foot is 1/a + 1/b, because every joint is shared between two boards. For 4'×8' board that is 1/4 + 1/8 = 0.375 LF/SF. Two independent routes to 0.37, which is the factor used here.
USG's figure covers flat joints. Inside corners are taped too and are not in it, which is why each area takes its inside-corner run as its own input — that footage is added to the tape total directly. It has to be: reaching a cut-up room's tape by inflating waste would drive the sheet count with it, and a 1,000 sq ft job needing about 620 LF would want 64% waste, buying 52 sheets where 35 are required.
Screws
GA-216-2010, the Gypsum Association's application specification, sets the spacing in §5.4: screws "not more than 12 in. o.c. for ceilings and 16 in. o.c. for walls where the framing members are 16 in. o.c.", and not more than 12 in. o.c. for both where framing is at 24 in. o.c. §8.4 applies the same spacing to single-layer board over steel framing.
Count it out on a 4'×8' sheet with framing at 16 in. o.c.: seven studs cross the 8-foot length, four screw rows fit across the 48-inch width, so 28 screws over 32 SF — 0.875 per SF. A ceiling at 12 in. o.c. comes to about 1.09 per SF. The 1.0 per SF used here sits between them and absorbs the misses and strip-outs that a geometric count does not.
Openings, waste and finish levels
Openings are deducted before the sheet count, using 21 SF for a door — a 3'0" × 7'0" leaf — and 15 SF for a window. The window figure is this calculator's default with nothing published behind it; take the real size off the schedule. Deducting openings and then carrying a waste percentage is the conventional pairing, because a sheet cut around a door rarely yields a usable offcut.
Waste is applied before the ceiling function, so it buys whole sheets. Finish level then drives compound and tape: Level 0 orders neither. The level descriptions follow GA-216-2010, which defers to GA-214, Recommended Levels of Gypsum Board Finish, for the definitions themselves. Specify the level from the drawings, not from what the walls will be painted with.
What this output must not be used for
This is a purchasing and pricing quantity, not a submittal and not a fire-rated assembly. The calculator does not know your assembly's UL or GA file number, does not check whether the board type, thickness, layer count and fastener schedule satisfy a required fire or acoustic rating, and does not size framing for height or deflection. Board type, stud gauge and fastener spacing in a rated wall come from the tested assembly, and that assembly governs over anything estimated here. Verify quantities against the drawings before ordering or bidding.
Frequently asked questions
32 square feet. The other common sizes are 4x10 at 40 SF, 4x12 at 48 SF, and the 54-inch-wide board used on commercial work at 36, 45 and 54 SF for 8, 10 and 12 foot lengths. Wider board is not free efficiency: it exists to put a tapered edge at the ceiling line of a 9-foot wall and cut out a butt joint, and it is heavier to handle.
Take the wall area, deduct the openings, divide by the square footage of one sheet, add waste, and round up to whole sheets. Wall area here is wall length times height, which is one face — a partition boarded on both sides is twice that. Then calculate compound, tape and screws off the sheets you are buying rather than the net area, because that is what will be on the truck. Verify the result against the drawings before you order.
USG publishes coverage for Sheetrock Brand All Purpose Joint Compound as approximately 10 gallons per 1,000 sq ft of gypsum panels, for the whole finishing operation rather than a single coat. On that rate a 4.5-gallon pail finishes about 450 SF of board and 5 gallons about 500 SF. A full Level 5 skim coat runs well above it, and lightweight compounds are rated slightly differently, so check the submittal sheet for the product you are actually buying.
About 28 on a wall framed at 16 inches on centre. GA-216-2010 §5.4 allows screws at not more than 16 inches on centre on walls at that framing spacing, which gives seven studs across the 8-foot length and four rows across the 48-inch width. On a ceiling the spacing tightens to 12 inches on centre and the count rises to about 35. These are maximum spacings from the application specification, not a preference — a rated or shear assembly may require a tighter schedule, and that schedule governs.
GA-216-2010 §5.4 states screws shall be spaced not more than 12 in. o.c. for ceilings and 16 in. o.c. for walls where framing members are 16 in. o.c., and not more than 12 in. o.c. for both ceilings and walls where framing is at 24 in. o.c. §8.4 applies the same spacing to single-layer board over steel framing. Those are maximums for ordinary construction. Fire-rated, shear and acoustically rated assemblies carry their own fastener schedules from the tested assembly, and where the two differ the tested assembly wins.
Material coverage figures on this page are taken from manufacturer submittal sheets — USG Sheetrock Brand All Purpose Joint Compound (J1969), the midweight version (J963) and Sheetrock Brand Paper Joint Tape (J1736). Fastener spacing is quoted from GA-216-2010, Application and Finishing of Gypsum Panel Products, published by the Gypsum Association; later editions exist but are not free to read, so the 2010 edition is what is cited. Finish level definitions belong to GA-214. The compound factors for Levels 1, 2, 3 and 5, the 15 SF default window opening and the framing allowances are this calculator's own assumptions and are identified as such above.