Drywall Calculator

This drywall calculator works out how many sheets of drywall you need for a room, and roughly how much joint compound, tape and screws go with them. Enter the room's length, width and wall height, or a total wall area, subtract doors and windows, and optionally add the ceiling.

Choose 4x8, 4x10 or 4x12 sheets and a waste percentage, and the sheet count updates as you type. The finishing supplies use common rules of thumb that are stated next to the results, so you can see exactly how each number is produced. Metric users can switch to meters and 1200 mm wide sheets.

How to Use the Drywall Calculator

1
Enter the room or wall area
Choose Room dimensions and type the length, width and wall height, or choose Total wall area and enter the square footage of the walls.
2
Add the ceiling if needed
Turn on Include the ceiling. With room dimensions it uses length times width; with total wall area you type the ceiling area.
3
Subtract openings
Enter the number of doors and windows. The defaults are 20 sq ft per door and 15 sq ft per window, and you can change both.
4
Pick a sheet size and waste
Choose 4x8, 4x10 or 4x12 sheets and set the waste percentage. 10% is the default; 15% suits rooms with many corners or openings.
5
Read the results
You get the number of sheets, the areas used, and estimates for joint compound (weight and pails), joint tape (feet and rolls) and screws.

How the drywall calculator works

For a rectangular room, wall area is the perimeter times the height. Door and window openings are subtracted and the ceiling, if included, is added. The net area is increased by the waste percentage and divided by the area of one sheet: 32 sq ft for 4x8, 40 for 4x10 and 48 for 4x12. The result is always rounded up to whole sheets.

Finishing supplies are based on the net area before waste, using widely quoted rules of thumb: about 138 lb of premixed all-purpose joint compound and about 370 ft of joint tape per 1,000 sq ft of drywall, and about one screw per square foot, which is roughly 32 screws per 4x8 sheet. Compound pails are counted at about 62 lb for a 4.5 gallon pail and tape at 250 ft per roll.

Net area = 2 × (length + width) × height − openings + ceiling
Sheets = ⌈net area × (1 + waste %) ÷ sheet area⌉
Compound (lb) = net area × 0.138 · Tape (ft) = net area × 0.37 · Screws = net area × 1

Worked example: a 12 x 14 ft room with the ceiling

Take a 12 x 14 ft room with 8 ft walls, one door, two windows, the ceiling included, 4x8 sheets and 10% waste.

Wall area: 2 × (12 + 14) × 8 = 416 sq ft.
Openings: 20 + 2 × 15 = 50 sq ft. Ceiling: 12 × 14 = 168 sq ft.
Net area: 416 − 50 + 168 = 534 sq ft.
Sheets: 534 × 1.10 ÷ 32 = 18.36, rounded up to 19 sheets of 4x8 (17 without waste). With 4x12 sheets it is 13.
Joint compound: 534 × 0.138 = about 74 lb, or 2 pails. Tape: 534 × 0.37 = about 198 ft, or 1 roll of 250 ft. Screws: about 534.

Drywall and supplies by area

Sheet counts include 10% waste. Supplies are based on the net area and rounded to whole numbers.

Net area	4x8 sheets	4x10 sheets	4x12 sheets	Compound	Tape	Screws
100 sq ft	4	3	3	14 lb	37 ft	100
250 sq ft	9	7	6	35 lb	93 ft	250
500 sq ft	18	14	12	69 lb	185 ft	500
1,000 sq ft	35	28	23	138 lb	370 ft	1,000
2,000 sq ft	69	55	46	276 lb	740 ft	2,000

Tips and common mistakes

Many pros do not subtract small openings, because the cut-out pieces are rarely usable. If you want a margin, set doors and windows to 0 or raise the waste to 15%.
Longer sheets mean fewer butt joints to tape, which saves finishing time, but a 4x12 sheet is heavy and hard to get up stairs and around corners. Hang ceilings first, then walls.
Screw spacing depends on where the board goes. Ceilings are usually fastened more closely than walls, so expect to use more screws overhead than the one-per-square-foot average.
Lightweight joint compound weighs less per pail than all-purpose, so count pails rather than pounds when you shop. You may also want a bag of setting-type compound for the first coat and for repairs.
Corner bead, fire caulk and adhesive are not included. Measure outside corners separately if you need bead.

Code and safety notes

Building codes set where fire-rated (Type X) drywall is required, for example on walls and ceilings between an attached garage and the living space in many jurisdictions, and moisture- or mold-resistant board is often used in bathrooms. Ceilings may need thicker board depending on framing spacing. Check your local code before you buy, and lift heavy ceiling sheets with a helper or a rented drywall lift.

Features

Room dimensions or total wall area, with an optional ceiling
Subtracts doors and windows with editable sizes
4x8, 4x10 and 4x12 sheets (or metric sheet sizes)
Adjustable waste percentage (default 10%)
Joint compound, tape and screw estimates from stated rules of thumb

Frequently Asked Questions

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

A 12 x 12 ft room with 8 ft walls has 384 sq ft of wall. Subtract one door (20 sq ft) and one window (15 sq ft) to get 349 sq ft. With 10% waste, that is 12 sheets of 4x8, 10 sheets of 4x10 or 8 sheets of 4x12. Adding the 144 sq ft ceiling brings it to 493 sq ft, or 17 sheets of 4x8.

How much joint compound do I need per sheet of drywall?

A common rule of thumb is about 138 lb of premixed all-purpose compound per 1,000 sq ft of drywall. For one 4x8 sheet (32 sq ft), that is about 4.4 lb. A 4.5 gallon pail weighing about 62 lb therefore finishes roughly 14 sheets. Rooms with many corners or poor seams will use more, and skim coating uses far more.

How many screws do I need for a sheet of drywall?

A 4x8 sheet usually takes about 32 screws on walls with studs 16 in on center, which works out to about one screw per square foot. That is the rule the calculator uses. Ceilings are often fastened more closely, so they use more. Follow the fastener spacing in the board manufacturer's instructions or your local code.

How much drywall tape do I need?

Plan on about 370 ft of joint tape per 1,000 sq ft of drywall, or about 12 ft per 4x8 sheet. For a 12 x 14 ft room with the ceiling, 534 sq ft of drywall needs about 198 ft of tape, which is one 250 ft roll. Inside corners use paper tape too, and they are included in this estimate.

How much extra drywall should I buy?

Add 10 to 15% to the net area. Use 10% for simple rectangular rooms and 15% for rooms with many corners, soffits, angled ceilings or openings. The calculator applies the waste percentage before dividing by the sheet area and rounds up, so the result already includes the extra. One or two spare sheets also help if a sheet breaks.

Should I use 4x8 or 4x12 drywall sheets?

Longer 4x12 sheets cover 48 sq ft each, so you hang fewer sheets and tape fewer butt joints, which gives a smoother finish with less work. They are heavy and awkward, though, and harder to carry into small rooms or up stairs. Many DIYers use 4x8 sheets for walls and small rooms, and 4x12 for long walls and ceilings with a helper.

Last reviewed September 21, 2026