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How Many Sheets of Drywall for a 20×20 ft Room with a 10 ft Ceiling?

A 20 by 20 foot room with a 10 foot ceiling needs this many 4×8 drywall sheets, with mud, tape and screws worked out. Here is the answer, plus a calculator you can adjust if your measurements are slightly different.

Answer: 26 sheets

How it changes with ceiling height

Same area, different ceiling height:

Ceiling height	8	9	10
Drywall sheets needed	21 sheets	23 sheets	26 sheets
Gross wall area	640 ft²	720 ft²	800 ft²

What a 20×20 ft room with a 10 ft ceiling actually involves

At 749 ft² this is a room you should stage rather than attack. 26 sheets is about 0.72 tons of board to move, cut and lift, and the taping will take two or three passes with drying time between them. Plan where the deliveries land and keep a clear working lane.

The room has 80 ft of wall around 800 ft² of gross surface. Knock off 51 ft² for openings and you are boarding 749 ft², or 824 ft² once your 10 percent waste allowance is added. That is 26 sheets of 4 ft × 8 ft board.

Deducting 1 door and 2 windows removes 51 ft², or 6 percent of the wall. That is about 2 sheets you do not buy. Cutting openings out of a hung sheet wastes the offcut, which is exactly what the waste allowance in this calculator is for — do not set it to zero and expect the cuts to come out even.

A 10 ft ceiling leaves a 24 in strip along the top after two 4 ft courses. That is a wide strip, not a sliver, so it is worth cutting it from a 4 ft × 8 ft sheet and using the rest rather than buying narrow board. At this height many crews hang 4 ft × 12 ft sheets vertically instead: one piece floor to ceiling, no rip and no horizontal joint, but roughly a quarter of each sheet ends up as offcut.

Where the square footage goes

Measured as	Amount	How it is worked out
Perimeter	80 ft	20 ft + 20 ft, doubled
Gross wall area	800 ft²	80 ft × 10 ft ceiling
Doors deducted	21 ft²	1 × 21 ft²
Windows deducted	30 ft²	2 × 15 ft²
Net area to board	749 ft²	gross minus openings
With 10% waste	824 ft²	the figure to buy against
4 ft × 8 ft sheets	26 sheets	824 ft² ÷ 32
4 ft × 12 ft sheets	18 sheets	824 ft² ÷ 48
Ceiling, if you board it	13 more sheets	20 × 20 = 400 ft², no openings to deduct

The room is square at 20 ft × 20 ft, which is the friendliest shape for boarding: every wall is the same length, so one cutting setup repeats four times and your offcuts stay useful.

Wall by wall

4 ft × 8 ft sheets hung horizontally, at a 10 ft ceiling, divide into 3 courses per wall:

Wall run	Surface	Pieces at 4 ft × 8 ft
4 × 20 ft wall	800 ft²	3 sheets per course × 3 = 9 per wall, 36 in total

Those are pieces, not sheets. Laid out literally the walls would take 36 pieces, against the 26 sheets you actually buy — the gap is the 4 ft offcut that comes off every 20 ft run and finishes the next course. It is the biggest saving available on a room this size, and it only works if you cut the long walls first and keep the offcuts.

At 20 ft by 20 ft the room is close to square, and this is the shape where the cutting sequence matters most. Every run leaves a 4 ft piece over, and that same piece is exactly what the next course needs — so cut the first sheet of each course down to the run length and start the next course with the offcut. Cut every course from a fresh sheet instead and you will buy three or four sheets you never needed.

A 20 ft run takes 3 sheets per course and leaves 4 ft of offcut every time.

Mud, tape and screws

Item	Quantity	Rule of thumb
Joint compound	3 gal	about 1 gal per 300 ft² for a level 4 finish
Joint tape	2 rolls	a 500 ft roll per 500 ft² of board
Drywall screws	907	about 1.1 per ft², roughly 32 per 4×8 sheet
Studs, if reframing	70	1 per ft at 16 in centres, plus 4 for corners and 2 per opening
Corner bead	as needed	one length per outside corner, inside and outside

Buy the mud in the largest tub that stays workable. A 3 gal job is 1 standard 4.5 gal bucket, and once a bucket is opened it skins over within days — powder you mix yourself keeps indefinitely and is cheaper per gallon on a job this size. Coat thin and build up: three thin passes sand far easier than two thick ones, and every extra pass costs you sanding time, not just mud.

How to hang it

Mark and check the studs. Board goes across them, so it does not matter if the spacing wanders — but it does matter that you can find them after the board is up.
Start at the top with a full 4 ft course, then the next full course, and finish with the 24 in rip at the bottom where it is easy to scribe to the floor.
Stagger the vertical joints. A joint that lines up with the one on the other side of a stud is the one that cracks first.
Keep the board about 1/2 in off a concrete floor and tight to the ceiling. Movement happens at the floor line, not at the ceiling.
Screw about 12 in apart in the field and every 8 in on the edges, driving the heads just below the surface without breaking the paper. A screw that tears the paper holds nothing.
Leave a 1/8 in gap at butt joints and fill it with mud before taping. Boards that are jammed tight buckle at the seam.
This room needs 26 sheets and roughly 907 screws. Order the sheets and the screws together — a shortfall of 20 screws is a wasted trip.

Which board to buy

1/2 in board is the default for walls and is what the count above assumes. Step up to 5/8 in for ceilings and for bedrooms where you want the room to feel quieter; it sags less at 24 in centres and takes screws better, at about 20 percent more weight per sheet. Use 1/4 in only for curves. For bathrooms, laundry rooms and basements use moisture-resistant board — it is not waterproof, and it still needs a proper waterproofing layer behind a tiled shower. Board that is going to sit in a garage or a shed is worth buying in 5/8 in for the impact resistance alone.

Common questions

How many sheets of drywall for a 20×20 ft room with a 10 ft ceiling?

26 sheets of 4 ft × 8 ft board, or 18 if you buy 4 ft × 12 ft sheets. The walls come to 749 ft² after deducting 1 door and 2 windows, and 824 ft² with your 10 percent waste allowance.

Do I need to add the ceiling?

Only if you are boarding it. The ceiling here is 400 ft², which is 13 more 4 ft × 8 ft sheets, roughly 53 percent on top of the walls. Ceilings take longer per sheet than walls — everything is overhead — so treat it as separate work, not extra work.

How do I hang drywall on a 10 ft ceiling?

Two full 4 ft courses plus a 24 in rip. Put the rip at the floor where it is easy to scribe, or at the top if the ceiling line is straight and the floor is not. Never put a narrow rip at the bottom on a floor that slopes.

How much joint compound and how many screws?

About 3 gallons of compound and 907 screws for this room, plus 2 rolls of tape. Buy a little more mud than the figure: a second coat always drinks more than the first, and running out mid-pass leaves a ridge you have to sand flat.

Should I hang drywall horizontally or vertically?

Horizontally, across the studs, unless you are using 4 ft × 12 ft sheets at a 10 ft ceiling. Horizontal hanging puts fewer joints in the middle of the wall, and every joint you can put at a height you can reach is a joint that is easier to finish. Vertical hanging is faster to put up and harder to finish.