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Drywall Calculator

Estimate how many sheets of drywall a room needs. Enter the room dimensions, pick a sheet size, and get sheet counts for walls and ceiling with waste included — plus rough screw and joint compound estimates.

Updated 2026-09-14
Room (feet)
ft
ft
ft

Longer sheets mean fewer joints to finish.

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Set to 0 to hang over openings

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%

Cuts and breakage. Angled rooms: 15–20%.

Choosing a sheet size

4×8 sheets are the default because one person can carry them and they fit in most vehicles. But if your walls are longer than 8 ft, 4×10 or 4×12 sheets hung horizontally can span a wall in one piece — fewer joints means dramatically less taping and mudding, which is where the real labor is. Ceilings almost always deserve the longest sheet you can handle.

Why sheets round up (and openings are tricky)

You can't buy 10.4 sheets, so every fraction becomes a whole sheet — that's already built in. Openings are less obvious: many hangers run drywall straight across doors and windows and cut the openings out afterward, which is faster and leaves stronger corners but "wastes" the cutout. If that's your plan, set doors and windows to 0 and let the waste allowance absorb the difference.

The default 10% waste suits a simple rectangular room. Rooms with angles, soffits, or stairwells routinely need 15–20%, and it's always cheaper to return a spare sheet than to make a second trip for one.

Sheets to buy
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Includes waste, rounded up
Wall area
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Ceiling area
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Total drywall area
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Sheets (exact fit)
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Screws (approx.)
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Joint compound (approx.)
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Screw and mud figures are rough rules of thumb.

Common questions

How do I measure a bedroom for drywall?

Measure the room's length, width, and wall height. Wall area = 2 × (length + width) × height. For a 12 ft × 12 ft bedroom with 8 ft ceilings that is 2 × 24 × 8 = 384 sq ft, plus 144 sq ft if you are hanging the ceiling too. Divide by 32 for 4×8 sheets and round up, then add waste.

How many sheets of drywall do I need for a 12x12 room?

Walls alone come to 384 sq ft — 12 sheets of 4×8, or 14 with a 10% waste allowance. Add the 144 sq ft ceiling and you are at 528 sq ft, about 17 sheets, or 19 with waste. Larger 4×12 sheets cut that to 11 sheets and leave far fewer joints to tape.

Should I subtract doors and windows?

Most installers do not. Standard practice is to hang the sheet straight over the opening and cut it out afterwards, which gives cleaner corners and fewer butt joints. Leave the door and window counts at zero to estimate that way; enter them if you are cutting sheets to fit.

What size drywall sheets should I use?

4×12 sheets on long walls mean fewer butt joints and less taping, but they weigh about 100 lb and need two people. 4×8 sheets are the practical choice for tight stairwells and solo work. Match the sheet length to your wall length where you can — a 12 ft wall takes one 4×12 with no seam.

How much waste should I plan for drywall?

Ten percent covers cuts, breakage, and corners in a plain rectangular room. Budget 15–20% for rooms with angled ceilings, many openings, soffits, or bump-outs, where offcuts rarely get reused.

How many screws and how much joint compound will I need?

Roughly one screw per square foot — about 32 per 4×8 sheet at standard 12–16 inch spacing. Joint compound runs about 0.053 lb per square foot of drywall, so a 500 sq ft room takes around 27 lb, or one 4.5-gallon bucket. Both are planning figures, not order-ready numbers.

How this is calculated

Method
Wall area = 2 × (room length + room width) × wall height. Ceiling area = length × width when included.
Openings are deducted at 21 ft² per door and 15 ft² per window. Many installers hang right over small openings and cut them out — keep the counts at 0 to estimate that way.
Sheets = total area ÷ sheet area (4×8 = 32 ft², 4×10 = 40 ft², 4×12 = 48 ft²), rounded up to whole sheets — you can’t buy a fraction of a sheet.
Sheets to buy applies the waste allowance first, then rounds up. Screws ≈ 1 per ft² (about 32 per 4×8 sheet); joint compound ≈ 0.053 lb per ft². Both are rough approximations.
Assumptions
  • Assumes a rectangular room with flat walls; closets, bump-outs, and stairwells should be measured separately and added.
  • The default 10% waste covers cuts, breakage, and awkward corners. Rooms with many angles need 15–20%.
  • Screw and joint compound quantities are rule-of-thumb approximations, not order-ready figures.
  • Sheet sizes are US standard; this calculator works in feet and inches only.
Sources
  • Gypsum Association / USG installation guidance — Standard fastener spacing (12–16 in) works out to roughly 28–36 screws per 4×8 sheet.
Methodology reviewed 2026-09-14 · See our methodology for how we build and test calculators.
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