Drywall Calculator
Sheets of drywall for a room's walls and ceiling by sheet size, with joint compound, tape and screw estimates from USG rules of thumb, waste factor and cost.
Drywall Calculator: with the default inputs, sheets to buy is 17.
About 20 sq ft each is deducted.
About 15 sq ft each is deducted.
Longer sheets mean fewer butt joints; 4 × 12 hung horizontally on an 8-ft wall leaves one seam.
Includes waste, rounded up.
- Drywall area
- 478 ft²Walls plus ceiling, less openings.
- Area with waste
- 526 ft²
- Joint compound
- 66 lbReady-mixed, about 138 lb per 1,000 sq ft — roughly one 4.5-gal pail per 450 sq ft.
- 4.5-gallon pails of compound
- 2
- Joint tape
- 177 ftAbout 370 ft per 1,000 sq ft; a roll is 250 or 500 ft.
- Drywall screws
- 478About 1 per sq ft on 16-in framing (32 per 4×8 sheet); a 1-lb box of 1¼-in screws holds ~300.
- Drywall cost
- $0.00
Assumptions
- Openings deducted at 20 ft² per door and 15 ft² per window.
- Compound, tape and screw rates assume a Level 4 finish on 16-in framing; ceilings and Level 5 use more.
- A 4.5-gallon pail of ready-mixed compound is taken as 61.7 lb.
| Material | Quantity | Note |
|---|---|---|
| Ready-mixed joint compound | ≈ 138 lb (2¼ pails of 4.5 gal) | Three coats, taped joints and screw heads. Setting-type (bag) compound: ≈ 85 lb. |
| Paper joint tape | ≈ 370 ft | About 1½ rolls of 250 ft. Mesh tape needs setting-type compound. |
| Screws, 1¼ in, 16-in framing | ≈ 1,000 | Walls 16 in o.c. on edges, 12 in in the field; ceilings 12 in throughout. |
| Corner bead | Measure outside corners | 8-ft or 10-ft sticks, metal or vinyl. |
| Primer | ≈ 3 gallons | New drywall drinks paint — PVA primer first. |
Based on USG and Gypsum Association estimating guidance; actual usage depends on framing spacing and finish level.
How this is worked out
The formula
Wall area = 2 × (length + width) × height − doors × 20 ft² − windows × 15 ft² Total area = wall area + (length × width if ceiling) Sheets = total area × (1 + waste %) ÷ sheet area, rounded up Joint compound ≈ 0.138 lb per sq ft Tape ≈ 0.37 ft per sq ft Screws ≈ 1 per sq ft
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Room length
- A number.in ft, in, m, cm · 0 or more · defaults to 12
- Room width
- A number.in ft, in, m, cm · 0 or more · defaults to 12
- Wall height
- A number.in ft, in, m, cm · 0 or more · defaults to 8
- Doors
- About 20 sq ft each is deducted.from 0 to 100 · whole numbers only · defaults to 1
- Windows
- About 15 sq ft each is deducted.from 0 to 100 · whole numbers only · defaults to 2
- Include the ceiling
- Turn this on or off.defaults to on
- Sheet size
- Longer sheets mean fewer butt joints; 4 × 12 hung horizontally on an 8-ft wall leaves one seam.4 × 8 ft (32 sq ft) · 4 × 10 ft (40 sq ft) · 4 × 12 ft (48 sq ft) · 4 × 9 ft (36 sq ft, for 9-ft walls)
- Waste factor(under More options)
- 10% for simple rooms; 15–20% with angles, soffits or many openings.a percentage · from 0 to 50 · defaults to 10
- Price per sheet(under More options)
- Leave 0 to skip cost.in dollars · 0 or more · defaults to 0
What you get back
- Sheets to buymain answer
- Includes waste, rounded up.
- Drywall area
- Walls plus ceiling, less openings.
- Area with waste
- Joint compound
- Ready-mixed, about 138 lb per 1,000 sq ft — roughly one 4.5-gal pail per 450 sq ft.
- 4.5-gallon pails of compound
- Joint tape
- About 370 ft per 1,000 sq ft; a roll is 250 or 500 ft.
- Drywall screws
- About 1 per sq ft on 16-in framing (32 per 4×8 sheet); a 1-lb box of 1¼-in screws holds ~300.
- Drywall cost
What this assumes
- Openings deducted at 20 ft² per door and 15 ft² per window.
- Compound, tape and screw rates assume a Level 4 finish on 16-in framing; ceilings and Level 5 use more.
- A 4.5-gallon pail of ready-mixed compound is taken as 61.7 lb.
About this calculator
Drywall is cheap; the labor and the second trip to the store are not. This calculator figures the board for a room from its dimensions, picks the sheet count for the size you can actually get through the door, and estimates the mud, tape and screws to finish it — using the same per-thousand-square-foot rules of thumb that USG and the Gypsum Association publish for estimators.
Sheet size matters more than count
An 8-ft wall takes two 4 × 8 sheets hung horizontally with one seam at 4 ft. The same wall with 4 × 12 sheets has the same horizontal seam but a third as many butt joints (the end-to-end joints that are hardest to hide). Fewer joints means less tape, less mud and a flatter wall. Use 12-footers wherever you can carry them in; 4 × 9 or 54-in-wide board exists for 9-ft walls. The calculator prices whatever you pick.
What gets deducted
Doors are deducted at 20 sq ft and windows at 15 sq ft, which is standard estimating practice. Many hangers don't deduct at all for openings under about 20 sq ft — the board around a window comes from one sheet with a hole cut in it, and the cutout is scrap either way. If your room has a lot of small windows, set the window count to zero to be safe. Closets, soffits and bulkheads are extra: run them as their own small rooms.
Waste
Ten percent covers a rectangular room. Go to 15–20% with cathedral ceilings, angled walls, lots of outlets and openings, or when you're hanging 12-footers in a room that isn't a multiple of 4 ft. Broken corners on delivery come out of this allowance too.
Finishing materials
The rules of thumb per 1,000 sq ft of board — about 138 lb of ready-mixed compound, 370 ft of tape and 1,000 screws — assume a standard Level 4 finish (tape, two fill coats, skim over screws) on 16-in framing. Setting-type "hot mud" weighs less per square foot because you don't lose water. Level 5 (full skim) adds another 50% to the compound. Screws go 16 in on centre at the edges and 12 in in the field on walls, 12 in throughout on ceilings; a 1-lb box holds about 300 1¼-in screws.
Reading the results
Sheets to buy is rounded up and includes waste. Compound is shown in pounds and as 4.5-gallon pails (61.7 lb each). Tape comes in 250-ft and 500-ft rolls. Corner bead, primer and the ceiling texture (if any) aren't included.
Frequently asked questions
▸How many sheets of drywall for a 12×12 room?
Walls are 384 sq ft less about 50 for a door and two windows, plus a 144 sq ft ceiling — 478 sq ft. With 10% waste that's 526 sq ft, or 17 sheets of 4 × 8 (11 sheets of 4 × 12).
▸How much joint compound do I need per sheet of drywall?
About 4.4 lb of ready-mixed compound per 4 × 8 sheet (138 lb per 1,000 sq ft), so a 4.5-gallon pail finishes roughly 14 sheets at a standard Level 4 finish.
▸How many screws per sheet of drywall?
About 32 for a 4 × 8 sheet on walls with 16-in framing (screws 16 in apart on the perimeter, 12 in in the field), and closer to 40 on a ceiling at 12-in spacing. Figure a pound of 1¼-in screws per 300 sq ft.
▸Should I hang drywall vertically or horizontally?
Horizontally on residential walls 8 ft or shorter — it puts the seam at a comfortable 4 ft for finishing, bridges more studs, and reduces the linear feet of joints by about 25%. Vertical hanging is common in commercial work and for walls over 9 ft.
▸Do I deduct doors and windows?
Estimators deduct 20 sq ft per door and 15 per window, which this calculator does. Many hangers ignore openings under 20 sq ft because the cutout is waste anyway; if in doubt, don't deduct the small windows.
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