Drywall · bathroom
How much drywall does a bathroom need?
A bathroom has more edges per square foot than anything else in the house. It also has two different boards in it, and the one people buy is usually the wrong one for the shower.
- Moisture-resistant board
- Wet-zone limits spelled out
- Higher waste, on purpose
The room
Openings
21 sq ft each
15 sq ft each
A linen closet you are not boarding, an archway. Anything under a couple of square feet is not worth deducting.
Sheet size
Thickness
Green board. Damp rooms only — not inside a shower or a steam enclosure.
Waste is 15%, 0 outside corners. Defaults are fine for most rooms.
Room plan
shape only, not to scale
You need
8sheets
4 × 8 ft · 1/2 in MR · 15% waste
Materials
$182
at your prices
- Walls
- 208 sq ft
- Ceiling
- 40 sq ft
- Openings
- −36 sq ft
- Net area to board
- 212 sq ft
- Sheets before waste
- 7 → 8
- Weight to carry
- 466 lb
What to put in the cart
Finishing follows the manufacturer coverage rates: 10 gal of mud and 370 ft of tape per 1,000 sq ft.
- 1$147
8 × 4 × 8 ft 1/2 in MR drywall sheets
- 2$9
1 × 1 lb box of 1-1/4 in drywall screws (about 195 screws)
- 3$7
1 × 250 ft roll of paper joint tape (79 ft needed)
- 4$19
1 × 4.5 gal pail of all-purpose joint compound (2.1 gal needed)
The whole setup lives in the link — send it to whoever is helping.
Your rooms
A renovation is never one wall. Save each room here and load it when you get to it — kept in this browser only, no account needed.
Nothing saved yet. Set up a wall above, then hit Save this room.
Worked example: An 8 × 5 ft bathroom, 8 ft ceiling, walls and ceiling
One door, one window, moisture-resistant 1/2 in board, 15% waste — higher than the other pages on purpose, because this room is nearly all edges.
| Walls | 208 sq ft |
| Ceiling | 40 sq ft |
| Openings | −36 sq ft |
| Net area to board | 212 sq ft |
| Sheets before waste | 7 |
| Sheets to buy | 8 |
| Screws | 195 (about 1 lb) |
| Paper tape | 79 ft (1 × 250 ft) |
| Joint compound | 2.1 gal (1 × 4.5 gal) |
| Weight on the truck | 466 lb |
| Heaviest single sheet | 58 lb |
Eight sheets for a room you can cross in three steps. Small rooms are inefficient — and driving out for one more sheet on a Sunday costs more than the extra 5% waste.
Turn the ceiling off and it drops to 7 sheets — that toggle is worth 1 sheets, or about 13% of the job.
Where these numbers come from
Three steps. Every coefficient is a published figure, so you can redo any of it on paper.
- 1
The room, then the ceiling
Walls are 2 × (8 + 5) × 8 = 208 sq ft; the ceiling is another 40. Take off one door and one window and you are boarding about 212 sq ft — a fifth of a garage, with four times the corners.
- 2
Fifteen per cent, not ten
A bathroom wall is interrupted by a door, a vanity, a mirror, a tub surround and often a window. Every one of those is a cut. The waste allowance here defaults to 15% and it is not padding — it is the difference between finishing on Saturday and driving out on Sunday.
- 3
MR board does not change the maths
Green board is the same 4 × 8 sheet size and nearly the same weight, so the count is identical to standard board. What changes is where it is allowed: damp rooms, not wet ones. The wet zone is a different product entirely.
Joint compound
10 gal
per 1,000 sq ft of board
Paper tape
370 ft
per 1,000 sq ft of board
Fasteners
16 in / 12 in
walls / ceilings, on centre
What this calculator cannot know
Four things the number has no way of seeing. Better to read them now than at the counter.
- It counts moisture-resistant board everywhere, which is more than the job needs. Ordinary board on the dry walls and MR only in the damp zone is cheaper and perfectly normal — the count stays the same, only the price per sheet changes.
- It does not plan the shower or tub surround. Those need cement backer board or a waterproof membrane system, not green board. That is a separate material with its own sheet sizes and its own maths.
- It cannot see the plumbing wall. A wall full of supply and drain pipes gets cut to ribbons, and the pieces between the pipes are often unusable. Add a sheet.
- It assumes the ceiling is flat and the room is rectangular. A sloped ceiling over a tub, or an alcove, is extra area the footprint does not show.
Questions people actually ask
Including the ones where the honest answer is “ask your inspector”.
How many sheets of drywall for a small bathroom?
An 8 × 5 ft bathroom with an 8 ft ceiling is 208 sq ft of wall and 40 sq ft of ceiling. Minus a door and a window, plus 15% waste, that is eight sheets of 4 × 8. It feels like a lot for a small room — it is the cuts, not the area.
Is green board required in a bathroom?
Not everywhere. Moisture-resistant board belongs on walls that get damp but not wet — behind a vanity, around a toilet, on a ceiling above a shower. Inside a shower or above a tub surround you need cement backer board or a bonded waterproof membrane. Green board is water-resistant, not waterproof, and it will fail if you treat it as waterproof.
Do bathroom ceilings need moisture-resistant drywall?
Yes, if there is a shower or tub in the room — that is where the steam goes. Standard board on a bathroom ceiling will show sagging seams and paint failure within a few years. The sheet count does not change, so this is purely a choice of which stack you pull from.
Why is the waste allowance 15% here?
Because of edge density. A bathroom has a door, a window, a vanity, a mirror, a tub and usually a plumbing wall, all within 200 sq ft. Each one is a cut and an offcut. Ten per cent works on a long empty wall; it does not work here.
How much mud for a bathroom?
At the published rate of 10 gallons per 1,000 sq ft, 212 sq ft needs a bit over two gallons — one 4.5 gal pail, with plenty left for the second and third coats. Buy the pail rather than the small tub; the small tubs cost more per gallon and you will run out mid-coat.
Boarding a different room?
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Who wrote this
Shawn Chen
I built these calculators and I keep them up to date. I am not a contractor, so treat this as arithmetic you can check yourself, not as advice from a tradesman.
Last checked and updated
Coverage and fastener figures are the manufacturers' published numbers; the sheet count is the standard area method used across the trade.
Where the numbers come from
- Gypsum Association — GA-216, Application and Finishing of Gypsum Panel Products
- USG — fastener spacing for gypsum board (16 in on walls, 12 in on ceilings)
- USG Sheetrock All Purpose Joint Compound — coverage figures
Coverage and spacing figures are the manufacturers’ own numbers. Where brands disagree, the page uses the lower one.