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Drywall Calculator

Total area divided into standard 4×8 sheet coverage, rounded up.

Wall/ceiling area (sq ft)

Sheets needed

Based on standard 4×8 ft drywall sheets (32 sq ft each).

What you entered

Wall/ceiling area (sq ft): 500

1
Divide by sheet area (4×8 ft = 32 sq ft)
500 ÷ 32= 15.625 sheets
2
Round up to a whole number of sheets
⌈15.625⌉= 16 sheets

Result

Sheets needed: 16

500 sq ft of wall/ceiling needs 16 standard 4×8 ft drywall sheets.

Drywall sheets needed for common room sizes with 8 ft ceilings

Wall area is the room perimeter times an 8 ft ceiling with no deduction for doors or windows, which is how most installers buy. Sheet counts are that area divided by the 32 sq ft in a 4 x 8 sheet, rounded up, exactly as the calculator does it.

Room size (ft)	Wall area at 8 ft ceiling (sq ft)	Ceiling area (sq ft)	Sheets for walls	Sheets for walls and ceiling
8 x 10	288	80	9	12
10 x 10	320	100	10	14
10 x 12	352	120	11	15
12 x 12	384	144	12	17
12 x 14	416	168	13	19
12 x 16	448	192	14	20
14 x 16	480	224	15	22
16 x 20	576	320	18	28
20 x 24	704	480	22	37

Counting gross wall area leaves a natural cushion, since the cutouts at doors and windows become offcuts rather than savings. A 9 ft ceiling raises every wall figure by about 12 percent, so recompute rather than reusing these rows. Sheets are 1/2 inch for walls and 5/8 inch for ceilings and fire-rated assemblies; moisture-resistant board belongs in bathrooms. Using 4 x 12 sheets instead cuts the number of seams to tape: divide your area by 48 rather than 32. Budget joint compound and tape separately, at roughly one 4.5 gallon bucket and 250 ft of tape per 12 to 15 sheets.

This doesn't account for waste from openings

Doors, windows, and outlets reduce the drywall actually needed, but most installers still buy full sheets and cut around openings — this calculator estimates from gross area, which tends to build in a reasonable natural buffer.

4×12 sheets reduce seams

Longer 4×12 sheets are available and reduce the number of seams to tape and mud on tall or long walls — if using a different sheet size, just divide your area by that sheet's square footage instead of 32.

Frequently asked questions

My room is 12x14 ft with 8-ft ceilings — how many sheets of drywall do I need?

The wall area is about 416 sq ft (2x12x8 + 2x14x8), minus roughly 40 sq ft for doors and windows = 376 sq ft. At 32 sq ft per 4x8 sheet, that's about 12 sheets. Most installers round up and buy 13-14 sheets.

Should I subtract for doors and windows?

Professional installers typically don't — they buy sheets to cover the gross wall area and cut around openings. The cutoff scraps become waste, but buying per gross area ensures you have enough and provides material for mistakes.

What thickness of drywall do I need?

1/2-inch is standard for walls. 5/8-inch is required for ceilings (to prevent sag) and for fire-rated walls (Type X). 1/4-inch is used for curved walls. Moisture-resistant (green board) or mold-resistant (purple board) for bathrooms.