Drywall Calculator
Calculate how many drywall sheets and materials you need.Calculate how many drywall sheets and materials you need — including waste and openings.
Getting your drywall order right
Deduct doors and windows from wall area, account for cutting waste, and check local code before choosing board type.
Working out drywall mud and tape
Joint compound — usually just called mud on site — is sold in buckets by weight. As a rule of thumb, allow roughly one 4.5-gallon bucket per 90 square feet of Sheetrock for a standard three-coat finish, plus about one 250 ft roll of paper tape per 135 square feet. This drywall mud calculator works both out automatically from your room dimensions, so you don’t have to estimate separately. If you would rather think in boards than in square feet, the per sheet figures are below.
Tiling a bathroom or kitchen wall instead of finishing it? Use the tile calculator for backsplash and shower surrounds.
How much mud per sheet of drywall
Coverage is normally quoted by the square foot, but almost nobody buys drywall that way. A standard 4 × 8 sheet is 32 square feet, so one 4.5-gallon bucket of joint compound covers roughly 3 sheets at a standard three-coat finish. A 4 × 12 sheet is 48 square feet, which works out closer to 2 sheets per bucket.
Those are starting figures, not guarantees. How much mud you actually get through depends on how many coats you run, how flat your framing is, and how heavy-handed you are with the knife. A level 5 finish uses noticeably more than a level 3.
The calculator works from your room dimensions rather than your sheet count, so it accounts for the offcuts and part-sheets a per-sheet estimate misses.
Related calculators
- concrete calculator — for basement and garage slabs under the walls.
- fence calculator — for exterior work on the same property.
- insulation calculator — what goes in the wall before the board
- Lumber Calculator — the framing behind the board
FAQFrequently asked questions
For walls only at 8 ft height, that’s about 2×(12+12)×8 = 384 sq ft. With 10% waste and 4×8 sheets (32 sq ft each), that’s roughly 14 sheets — add the ceiling for a full room.
4×8 sheets are easiest to handle alone. 4×12 sheets mean fewer seams but need two people and more room to maneuver.
10% is standard. Rooms with many openings, angled walls, or complex cuts often need 15–20%.
Joint compound — commonly called mud — is estimated here at roughly one 4.5-gallon bucket per 90 sq ft of drywall. Actual usage varies by number of coats and finish level.
Roughly one 4.5-gallon bucket per three 4 × 8 sheets, or per two 4 × 12 sheets, at a standard three-coat finish. That comes from coverage of about one bucket per 90 square feet. Your actual usage moves with the number of coats and the finish level you are going for, and a level 5 finish uses considerably more than a level 3.
Sheetrock is a brand of drywall made by USG, used so widely in the US that the name is often used generically. The calculations are identical — sheet sizes, mud coverage and screw spacing don’t change between brands.
We estimate about one 250 ft roll per 135 sq ft of drywall — adjust based on how many seams your layout actually has.
1/2" is standard for most walls and ceilings. 5/8" (often fire-rated) is common for garages, shared walls, and some ceiling spans — check local code.
| Thickness | Typical use |
|---|---|
| 1/2 inch | Standard for most walls and ceilings |
| 5/8 inch | Fire-rated applications, garages, ceilings with wider joist spacing |
A standard 1/2-inch 4 × 8 sheet weighs around 51 lb, and 5/8-inch fire-rated board is substantially heavier at roughly 70 lb. Lightweight 1/2-inch board runs closer to 40 lb. Weight matters more than people expect: it decides whether one person can hang a ceiling alone, whether your vehicle can carry the load, and whether the delivery needs to come off the truck mechanically. Figures vary by manufacturer, so check the spec sheet for the board you are actually buying.
Bathrooms, laundry rooms and other humid spaces typically benefit from moisture-resistant board — it is not automatically required everywhere.
Many jurisdictions require fire-rated board on garage walls/ceilings shared with living space — check your local building code before ordering.