Surfaces & finishes · free tool
Drywall Calculator
How much drywall do you need? Enter your room, pick your sheet size, and get the sheets to buy — plus mud, tape, screws and cost.
Drywall Calculator
How many sheets you need — plus mud, tape & screws.
1 Your space
2 Drywall to buy
About 2 buckets of ready-mix (4.5 gal) and 1 roll of 250-ft tape. Estimates only — roughly 0.5 gal mud, 40 ft tape and 32 screws per 4x8 sheet; mud varies with coats and finish.
Estimates only — material coverage varies; most pros don't deduct doors and windows and buy 10% extra. See how we calculate · Updated monthly
Method · how it works
How to calculate how much drywall you need
Wall and ceiling area, plus a little waste, divided by what a sheet covers. Here is exactly what the calculator does.
Find the area
Walls are 2 × (L + W) × H; add the ceiling (L × W) if you're covering it.
Skip the openings
Most pros don't subtract doors and windows — you cut them from full sheets and reuse the offcuts.
Add waste
Add ~10% for cuts and breakage — 15% for busy layouts, 20% for lots of soffits and angles.
Divide by sheet size
Divide by the sheet's coverage (4x8 = 32 ft²) and round up to whole sheets.
A 12 × 12 ft room, 8 ft ceilings + ceiling
+ ceiling 12 × 12 = 528 ft²
528 × 1.10 = 580.8 ft²
580.8 ÷ 32 = 18.2 sheets
4x8 sheets, 10% waste in
Sources: sheet coverage (4x8 = 32 ft²) · USG / manufacturer specs · square footage method
Verified against standard drywall references · Updated monthly
Estimates only. Material coverage and finish vary — buy about 10% extra, and remember longer sheets mean fewer joints to tape and finish.
Sheets · by room size
How many sheets for a room?
A quick guide in 4x8 sheets, with the ceiling included and 10% waste. For your exact room, use the calculator above.
420 sq ft of walls + ceiling — a small bedroom.
+ ceiling528 sq ft — a standard bedroom.
+ ceiling640 sq ft — a large bedroom or den.
+ ceiling764 sq ft — a living or family room.
+ ceiling896 sq ft — a great room or garage.
+ ceiling384 sq ft — walls only, no ceiling.
walls onlySwitch to 4x12 sheets and the counts drop by about a third — fewer sheets, fewer joints to tape.
Sheet size
4x8 vs 4x12 drywall sheets
Sheets come in 4x8, 4x9, 4x10 and 4x12. Bigger sheets cover more and leave fewer seams — but they're heavier and harder to handle.
Easy to handle — one person can carry and hang them, and they fit through tight halls and stairwells.
More seams to tape and finish — more butt joints across an 8 ft wall.
~54 lb per 1/2 in sheet. Best for small rooms, repairs and DIY.
Fewer sheets & fewer joints — a 12 ft wall goes up with no butt joint, so far less taping and finishing.
Heavy and awkward — usually a two-person lift, and may not fit tight spaces.
~82 lb per 1/2 in sheet. Best for big rooms, long walls and pros.
Rule of thumb: 4x8 for tight spaces and DIY, 4x12 for large open rooms where less taping saves real time. Switch sizes in the calculator to compare.
Finishing materials
Joint compound, tape & screws
Sheets are only half the list — you also need mud, tape and screws to hang and finish. The calculator's Materials tab estimates all three from your area.
Joint compound (mud)
~0.5 gal / sheetPlan about half a gallon per 4x8 sheet for a full three-coat finish — roughly a 4.5-gal bucket per ~9 sheets. Lighter finishes use less; textured walls use more.
Tape
~40 ft / sheetOne foot of tape covers about 2-3 sq ft of drywall — roughly 40 ft per 4x8 sheet. A single 250-ft roll handles a small room.
Screws
~32 / sheetAbout 1 screw per square foot — roughly 32 per 4x8 sheet (12 in in the field, 8 in on edges). A 1-lb box holds ~200.
These are estimates — joint compound especially varies with the number of coats and the finish level, so check your product's coverage and round up to whole buckets, rolls and boxes.
Getting the count right
Do you subtract doors and windows?
The two questions that trip people up: whether to deduct openings, and how much extra to buy. Here's the pro take on both.
Openings
Usually, don't deduct them
Most drywallers hang full sheets right over door and window openings, then cut them out afterward. The offcuts get reused for closets, patches and short pieces — so subtracting openings often leaves you short.
The calculator keeps openings in by default. Only subtract them for a big feature wall or a room dominated by glass, where the waste would be real.
Waste
How much extra to buy
Buying a couple of extra sheets is cheaper than a second trip — and leftover drywall is handy for future patches. After hanging, it's on to paint.
Answers
Drywall calculator FAQs
How many sheets of drywall do I need for a room?
Add the wall and ceiling area, add ~10% waste, and divide by the sheet coverage. A 12 x 12 room with a ceiling needs about 19 sheets of 4x8.
How big is a sheet of drywall?
The most common is 4 x 8 ft (32 sq ft). It also comes in 4x9 (36), 4x10 (40) and 4x12 (48 sq ft), in 1/4, 1/2 and 5/8 in thicknesses.
Do I subtract doors and windows?
Usually no — pros hang full sheets and cut openings out afterward, reusing the offcuts. Only deduct for a wall that's mostly glass or a big feature opening.
How much joint compound, tape and screws do I need?
Roughly 0.5 gal of mud, 40 ft of tape and 32 screws per 4x8 sheet — about a bucket of mud per 9 sheets and a 250-ft roll of tape per small room.
Is drywall the same as sheetrock?
Yes — Sheetrock is a brand of drywall (like Kleenex for tissue). Drywall, sheetrock, wallboard and gypsum board all mean the same panel.
How much waste should I add?
10% for simple rooms, 15% for busy layouts with lots of corners, and 20% for complex ceilings, soffits and angles.
How much does a sheet of drywall weigh?
A 4x8 1/2 in sheet is about 54 lb; a 4x12 is about 82 lb. Larger sheets cover more but usually need two people to carry.
Should I use 4x8 or 4x12 drywall?
4x8 for tight spaces, repairs and DIY; 4x12 for long open walls, where fewer butt joints mean much less taping and finishing.