Drywall details
Type feet and inches like 12'6" or just 12.5. Use Whole room for four walls, or add single walls and a ceiling. Everything is saved on this device.
About the drywall calculator
This free drywall calculator tells you how many sheets of drywall you need. Enter each room (four walls at once), single walls or a ceiling. The calculator takes off the doors and windows, adds extra for cuts, and rounds up to whole sheets.
It also gives rough amounts of joint compound, tape and screws, and the weight of the sheets, so you know what you are carrying.
Features
- Whole rooms, single walls and ceilings — mix them in one list
- Doors and windows — pick a standard size and set how many; they are taken off
- Sheet sizes — 4 × 8, 4 × 10 and 4 × 12 ft (1.2 × 2.4 to 3.6 m in metric)
- Thickness — 1/2 in, 5/8 in or 1/4 in, with the weight of one sheet
- Waste — 5%, 10% or 15% for cuts
- Finishing supplies — joint compound, tape and screws, marked as estimates
- Cost — enter a price per sheet
- Copy the list — a shopping list for the store
How to use it
- Choose Feet & inches or Metres & cm
- Pick Whole room, One wall or Ceiling and type the sizes. Use Add another room or wall for more
- Type how many doors and windows each wall has
- Choose the sheet size and thickness
- Tick Hang the ceiling too if the ceiling is new
- Read the sheets and press Copy the list
Sheet size and thickness
Longer sheets mean fewer joints to tape, but they are heavy and hard to carry:
| Sheet | Area | 1/2 in weight | 5/8 in weight |
|---|---|---|---|
| 4 × 8 ft | 32 sq ft | about 54 lb | about 70 lb |
| 4 × 10 ft | 40 sq ft | about 68 lb | about 88 lb |
| 4 × 12 ft | 48 sq ft | about 82 lb | about 105 lb |
Use 1/2 in for normal walls. Use 5/8 in on ceilings, where it sags less, and where fire rules need it. 1/4 in is for curves and for covering an old wall. The weights are estimates; brands differ.
Worked examples
These numbers come from the calculator:
| Job | Sheets |
|---|---|
| Room 10 × 10 × 8 ft, 1 door, 1 window, walls only, 4 × 8, 10% | 10 sheets (290 sq ft) |
| Room 12 × 12 × 8 ft, same, walls only | 13 sheets (354 sq ft) |
| Room 12 × 12 × 8 ft, with the ceiling | 18 sheets (498 sq ft) |
| One wall 20 × 8 ft, 1 door, 1 window, 4 × 12, 5/8 in, 5% | 3 sheets (130 sq ft), 105 lb each |
| Metric room 4 × 3 × 2.4 m, ceiling, 1.2 × 2.4 m sheets | 17 sheets (42.5 m²) |
Check the 12 × 12 room: the walls are 48 ft around × 8 ft = 384 sq ft. A 32 × 80 in door is 17.8 sq ft and a 36 × 48 in window is 12 sq ft. That leaves 354 sq ft. With 10% extra it is 389 sq ft, and 389 ÷ 32 = 12.2, so you buy 13 sheets.
Joint compound, tape and screws
These are rules of thumb, so the calculator labels them estimates:
- Joint compound: one 4.5 gallon bucket (17 L) for about 450 sq ft of finished drywall
- Tape: about 0.375 ft of tape for each sq ft, in 500 ft rolls (90 m in metric)
- Screws: about 1 lb for each 100 sq ft
Pros often buy a little more, because each coat needs mud and sanding wastes some. A pre-mixed bucket and a roll of tape are cheap, so round up.
Frequently asked questions
How many sheets of drywall do I need?
Find the wall and ceiling area, take off doors and windows, add 10%, and divide by the area of one sheet. Round up. A 12 × 12 ft room with 8 ft walls needs 13 sheets for the walls.
Should I subtract windows and doors?
Yes, the calculator does. Some builders skip small windows, because cutting around an opening wastes board. The extra waste setting covers this.
How much waste should I add?
10% is the normal figure. Use 5% for a plain rectangle and 15% for a room with many corners.
What is the best sheet size?
A 4 × 8 sheet is easiest to carry. On a tall wall or a ceiling, a 4 × 12 sheet gives fewer joints, but you need a helper.
What is the difference between drywall and sheetrock?
Sheetrock is a brand name. It is the same board that is also called gypsum board or plasterboard.
How many screws are in a sheet?
About 32 for a 4 × 8 sheet, spaced 16 inches apart on the studs. 1 lb per 100 sq ft is a safe guide.
Good to know
- Measure wall height from floor to ceiling, not the stud length.
- Hang ceilings first, then walls.
- Joint compound, tape and screws are estimates. The sheets are the number to trust.
- Check local fire rules before choosing thickness.
- Everything stays on your device.
Related tools
- Paint Calculator — paint for the finished walls
- Wallpaper Calculator — rolls for the same walls
- Square Footage Calculator — the area of any room
- Flooring Calculator — boxes for the floor
- Roofing Calculator — shingles for the roof
