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

With 8 ft walls, the four walls are 4 × 12 × 8 = 384 sq ft — 12 sheets of 4 × 8 — and the ceiling is 144 sq ft, 4.5 more. That is 16.5 sheets before waste; with 10%, 19.

How many square feet is a sheet of drywall?

A 4 × 8 ft sheet is 32 sq ft (2.97 m²), a 4 × 10 is 40 sq ft and a 4 × 12 is 48 sq ft.

Should I use 4 × 8 or 4 × 12 sheets?

The area is the same, but 12 ft sheets span a 12 ft wall in one piece and leave fewer seams to tape. They are heavier and harder to carry, which is why 4 × 8 is the default.

Do I subtract doors and windows?

For large ones, yes — enter their total area; an 80 × 36 inch door is 20 sq ft (1.9 m²). Small windows are often left in, since the sheet over them is cut out anyway.

How many sheets do I need for a ceiling?

The room's length × width divided by one sheet's area. A 12 × 14 ft ceiling is 168 sq ft: 5.25 sheets of 4 × 8, so 6 — or 4 sheets of 4 × 12, with fewer joints to tape overhead.

Drywall Calculator: How Many Sheets (4×8, 4×10, 4×12)

Drywall sheets for a wall or room from its size and the sheet size, with doors and windows taken off.

Inputs

Wall length(m)

0.1 m50 m

Wall height(m)

0.1 m6 m

Doors and windows to leave out(m²)

0 m²500 m²

Sheet size

Waste allowance(%)

0 %50 %

Units

Include CalculateEveryday mark

Drywall sheets

Working: 9.6 m² ÷ 2.97 m² a 4 × 8 ft sheet = 3.23, + 10% = 3.55 → 4
Wall area to cover: 9.6 m²
Sheet size: 4 × 8 ft (2.97 m²)
Without waste: 4

One face of one wall. A partition needs both faces; a ceiling is its own area.

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What each Drywall input means

Wall length: The wall's length, in metres or feet. For a whole room, add the lengths of all the walls: the perimeter.
Wall height: The wall's height, floor to ceiling.
Doors and windows to leave out: The area of doors and windows to subtract, in m² or sq ft. Small windows are often left in, since the sheet over them is cut out anyway.
Sheet size: 4 × 8, 4 × 10 or 4 × 12 ft — 32, 40 or 48 sq ft. Longer sheets cover the same area with fewer seams.
Waste allowance: Extra for off-cuts and mistakes; 10% is common, more for rooms full of corners and openings.
Units: Metric (metres, m², litres) or US units (feet, square feet, gallons). Wall sizes switch with it; the sheet sizes stay the same 4 ft widths either way.

Drywall formula

sheets = (length × height − openings) ÷ sheet area × (1 + waste %), rounded up

n = \left\lceil \frac{l \times h - A_{\text{open}}}{A_{\text{sheet}}} \times \left(1 + \frac{p}{100}\right) \right\rceil

Drywall is sold in 4 ft-wide sheets, most often 8 ft long (32 sq ft), with 10 ft (40 sq ft) and 12 ft (48 sq ft) lengths for taller walls and fewer joints. Measure each wall as length × height, take off any large openings, and divide by one sheet's area; add the cut waste and round up. A room is the sum of its walls plus the ceiling, and a partition wall that will be finished on both sides counts twice. Longer sheets do not change the area — they cut down the number of seams to tape and the off-cuts at the end of each row.

Drywall worked example

A 4 × 2.4 m wall is 9.6 m², or 103 sq ft. A 4 × 8 ft sheet covers 32 sq ft (2.97 m²), so 103 ÷ 32 = 3.23 sheets; with 10% for cuts that is 3.55, so 4 sheets. A whole 4 × 4 m room — four such walls and the ceiling, 54.4 m² — comes to 18.3 sheets, 21 with 10%.

More Drywall examples

A 12 ft wall, 8 ft high, with a 20 sq ft door: 96 − 20 = 76 sq ft, which is 2.38 sheets of 4 × 8, 2.61 with 10% — 3 sheets.

A 5 m wall 2.7 m high, taller than an 8 ft sheet, with 2 m² of window: 11.5 m² ÷ 3.72 m² per 4 × 10 ft sheet = 3.09, so 4 sheets with the 10% allowance.

Where the Drywall calculator can give the wrong answer

Both faces of a partition: double the wall, or run it twice.
The ceiling is its own area (room length × width). Ceiling board is often a different product, so count it separately.
Cut waste depends on the layout. Rooms with many windows, angles or short walls waste more than a long plain wall.
Joint compound, tape and screws scale with the sheets but are not counted here.

Spotted a mistake? Tell us

Drywall reference table

4 × 8 ft sheets for whole rooms with 8 ft walls, openings not subtracted
Room	Wall area	Ceiling area	Sheets, walls + ceiling	With 10% extra
10 × 10 ft	320 sq ft	100 sq ft	13.1	15
12 × 12 ft	384 sq ft	144 sq ft	16.5	19
12 × 14 ft	416 sq ft	168 sq ft	18.3	21
14 × 16 ft	480 sq ft	224 sq ft	22	25
16 × 20 ft	576 sq ft	320 sq ft	28	31

Source: Arithmetic: walls = 2 × (length + width) × 8 ft, ceiling = length × width, ÷ 32 sq ft a sheet, rounded up after the extra

Drywall FAQ

: With 8 ft walls, the four walls are 4 × 12 × 8 = 384 sq ft — 12 sheets of 4 × 8 — and the ceiling is 144 sq ft, 4.5 more. That is 16.5 sheets before waste; with 10%, 19.
: A 4 × 8 ft sheet is 32 sq ft (2.97 m²), a 4 × 10 is 40 sq ft and a 4 × 12 is 48 sq ft.
: The area is the same, but 12 ft sheets span a 12 ft wall in one piece and leave fewer seams to tape. They are heavier and harder to carry, which is why 4 × 8 is the default.
: For large ones, yes — enter their total area; an 80 × 36 inch door is 20 sq ft (1.9 m²). Small windows are often left in, since the sheet over them is cut out anyway.
: The room's length × width divided by one sheet's area. A 12 × 14 ft ceiling is 168 sq ft: 5.25 sheets of 4 × 8, so 6 — or 4 sheets of 4 × 12, with fewer joints to tape overhead.