Drywall Calculator

How many sheets of drywall do you need? Divide the total wall and ceiling area by one sheet's coverage (a 4' x 8' sheet covers 32 sq ft), then add 10% for waste and round up. A 20' x 15' room with 9-foot ceilings, ceiling included, is about 930 sq ft, or 32 sheets of 4x8 (plus about 1,160 screws, 3 boxes of ready-mixed joint compound and 2 rolls of tape). This drywall calculator builds that full shopping list from your room's dimensions.

Working on the whole room? The Paint Calculator turns the same wall area into gallons for the finish coat, the Concrete Calculator sizes a slab or footing under it, and the Roofing Calculator plus Roof Pitch Calculator handle the shell overhead; use this page for interior gypsum board and those for the surfaces around it.

How the sheet count is calculated

The number of sheets comes from total area divided by the area of one sheet, with a waste allowance:

Wall area is the room's perimeter times its ceiling height: 2 × (length + width) × height. Ceiling area is simply length × width (only added if you tick "include the ceiling"). A standard 4' x 8' sheet covers 32 sq ft, a 4' x 9' covers 36, a 4' x 10' covers 40, and a 4' x 12' covers 48 sq ft. Multiplying by 1.10 adds the 10% waste factor, and the result is rounded up because you cannot buy a fraction of a sheet.

Drywall sheet sizes and coverage

Bigger panels cover more and leave fewer seams, but weigh more. This quick reference shows each common size's coverage, how many you need per 100 sq ft of surface (with the 10% waste factor baked in), and the screws and tape one sheet takes at USG's estimating rates.

Sheets-per-100 figures include the 10% waste factor. Screws (1.25 per sq ft) and tape (0.37 ft per sq ft) follow USG's Sheetrock Wallboard Estimator. Weight depends on thickness and product line (lightweight 1/2" board is lighter than standard), so check the data sheet before you carry big sheets up stairs.

A worked example with real numbers

Take a 20' x 15' bedroom with 9' ceilings and assume you are drywalling the walls and the ceiling using 4x8 sheets:

• Perimeter: 2 × (20 + 15) = 70 ft.
• Wall area: 70 ft × 9 ft = 630 sq ft.
• Ceiling area: 20 ft × 15 ft = 300 sq ft.
• Total area: 630 + 300 = 930 sq ft.
• Raw sheets: 930 ÷ 32 = 29.1 sheets.
• With 10% waste: 29.1 × 1.10 = 32.0, rounded up to 32 sheets.

Switch to 4x12 sheets and the same 930 sq ft needs only 930 ÷ 48 = 19.4 raw, or 22 sheets after waste: fewer panels, fewer seams to tape, but heavier to carry.

How many sheets of drywall per room size

These are the full material totals for common rooms with a 9-foot ceiling, walls plus ceiling included, and the standard 10% waste factor. Surface area is 2 × (length + width) × 9 for the walls plus length × width for the ceiling; screws, mud and tape follow the same USG-based rates the calculator uses.

For walls-only jobs, subtract the ceiling area (length × width) before dividing. Screws are a count (1.25 per sq ft); mud is 4.5-gallon ready-mix boxes at 10 gal per 1,000 sq ft; tape is 250 ft rolls at 370 ft per 1,000 sq ft.

How to measure your room

You only need three measurements to get a solid estimate. Work through them in order:

1. Length and width: measure the two floor dimensions of the room in feet. For an irregular room, break it into rectangles and add the areas; the Square Footage Calculator helps if the shape is awkward.
2. Ceiling height: measure floor to ceiling in feet, in more than one spot if the floor or ceiling is out of level.
3. Sheet size: pick the panel size your store stocks and you can realistically handle.
4. Ceiling toggle: turn it on if you are drywalling the ceiling, off if it already has a finished ceiling or drop tiles.

The results update as you type: read the sheet count at the top, then scroll to the materials estimate and shopping list for screws, compound and tape.

How to estimate fasteners, mud and tape

Sheets are only part of the job. The calculator also estimates the consumables that make a wall look finished, using the rates per 1,000 sq ft of board from USG's Sheetrock Wallboard Estimator (which includes no waste allowance):

• Screws: 1,250 per 1,000 sq ft of board, or 1.25 per square foot (40 for a 4x8 sheet). Board makers' installation guides space them no more than 12 inches apart on ceilings and no more than 16 inches on walls framed 16 inches on center.
• Joint compound (mud): 10 gallons of ready-mixed compound per 1,000 sq ft, so one 4.5-gallon box covers about 450 sq ft for taping and finishing coats. USG's own FAQ puts it at about two 4.5-gallon pails per 1,000 sq ft, so the estimate leaves a little margin.
• Joint tape: 370 linear feet per 1,000 sq ft of board (0.37 ft per sq ft); the calculator counts 250-foot rolls.

A second worked example: walls only, 4x12 sheets

Now picture a 16' x 14' living room with 9' ceilings where the ceiling is already finished, so you are hanging the walls only and you have a helper, so you choose 4x12 sheets. Work it through the same way:

• Perimeter: 2 × (16 + 14) = 60 ft.
• Wall area: 60 ft × 9 ft = 540 sq ft (no ceiling this time).
• Raw sheets: 540 ÷ 48 = 11.25 sheets.
• With 10% waste: 11.25 × 1.10 = 12.4, rounded up to 13 sheets of 4x12.

That same 540 sq ft in 4x8 panels would be 540 ÷ 32 = 16.9 raw, or about 19 sheets after waste. The 4x12 choice saves six panels and, more importantly, cuts the number of end joints along each row by about a third (a 60 ft run takes 5 sheets instead of 7.5), which means less tape, less mud and less sanding. The trade is weight: a 4x12 sheet is half again as heavy as a 4x8 of the same board, so you want two people and a clear path to the wall.

What it costs to drywall a room

The sheet count is the input to a budget, so attach your local prices. Drywall pricing moves with the market and differs by store and region, so this page does not quote market prices. As an illustration with placeholder prices, take the 32-sheet room from above: at $15 a sheet that is $480 in board, plus 3 boxes of mud at $16 ($48) and 2 rolls of tape at $6 ($12), about $540 in materials before screws, corner bead, primer and paint. To convert any of these counts into a dollar figure, multiply the quantity by your local store price; the calculator gives you the quantities, and a quick check of current shelf prices gives you the rest. If you also need to budget the finish coat, the Paint Calculator turns the same wall area into gallons and a paint cost.

Cost to sheetrock a house by board area

To estimate a whole-house or large-job material budget, work from total board area (add up every room's wall and ceiling surface). The table below assumes placeholder prices of $15 per 4x8 sheet, $16 per 4.5-gallon mud box and $6 per 250 ft tape roll; swap in your own local shelf prices, since drywall pricing moves with the market. These are material estimates only and exclude screws, corner bead, primer, paint and labor.

Estimates only. Prices are placeholder assumptions ($15/sheet, $16/mud box, $6/tape roll), not quoted rates; check current store prices. Screws are listed as a count (1.25 per sq ft) and are not priced. Measure every wall and ceiling to get your own board area.

From hanging to finishing: the full workflow

Buying the right quantities is step one; knowing where each material goes makes the estimate make sense. A typical job runs in this order:

1. Hang the ceiling first, then the walls. Ceiling panels go up before walls so the wall sheets help support the ceiling edges. This is where most of your sheet count and screw weight is used.
2. Screw off every sheet. Fasteners go into every framing member, no more than 12 inches apart on ceilings and 16 inches on walls framed 16 inches on center; USG's estimator plans 1,250 screws per 1,000 sq ft.
3. Tape the seams. Embed joint tape in a first coat of mud over every seam and inside corner; USG's estimator plans 370 ft of tape per 1,000 sq ft.
4. Apply the finishing coats. A tape coat plus two finish coats, sanding between; USG's estimator plans 10 gallons of ready-mixed compound per 1,000 sq ft.
5. Add corner bead, then prime and paint. These are outside the calculator's quantities but belong in your budget.

Seeing the workflow explains why the calculator estimates four separate materials: sheets for hanging, screws for fastening, and mud plus tape for finishing. Skip any one and the wall is not done.

Drywall thickness and type, explained

Thickness never changes the sheet count (a 9' x 12' wall needs the same number of panels whether they are 1/2" or 5/8"), but it changes the weight you carry and the product you buy. Here is how the common options are used:

• 1/2 inch: the usual board for house walls and ceilings. Georgia-Pacific's installation guide calls for its 1/2-inch lightweight or sag-resistant ceiling board in residential work, including on joists 24 inches on center.
• 5/8 inch (Type X): the fire-rated board used in fire-rated assemblies. IRC Table R302.6 requires it on a garage ceiling below habitable rooms; the other walls and ceilings between a house and an attached garage need at least 1/2-inch board on the garage side. Heavier, so plan for a helper.
• Moisture- and mold-resistant ("green board" / purple board): for bathrooms, laundry rooms and basements. For tiled wet areas, cement board is used instead behind the tile.
• 1/4 and 3/8 inch: thin, flexible board for curved walls or for skinning over an existing surface during a remodel.

Match the type to the room before you buy: the calculator tells you how many panels, but code and location decide which panels.

Who this calculator is for

This tool is built for anyone turning a bare room into a materials list. That includes:

• DIY homeowners finishing a basement, garage, attic or spare bedroom.
• Renovators patching or re-hanging walls after removing old plaster or paneling.
• Contractors and handymen who want a fast sanity check before writing a materials order.
• Budget planners estimating cost by multiplying sheet and consumable counts by store prices.
• First-timers who have never bought drywall and want to avoid over- or under-buying.

Key terms explained

• Square foot (sq ft): the unit of area used throughout. A 4x8 sheet is 32 sq ft.
• Waste factor: the percentage added for offcuts, breakage and mistakes: 10% here, often 15% for complex rooms.
• Gross wall area: perimeter times height, without subtracting doors or windows. It runs slightly high on purpose.
• Joint compound (mud): the paste used to fill seams and screw dimples and to embed tape; "ready-mix" comes pre-mixed in boxes or buckets.
• Type X: fire-rated gypsum board (5/8 inch in the IRC garage rule) used where a code or a fire-rated assembly calls for it. It does not change the sheet count.
• Field vs. edge: the "field" is the middle of a sheet over studs; "edges" are the perimeter. Both get screwed.

Three quick scenarios

The same room can need very different amounts depending on your choices:

• Walls only, 4x8: a 12' x 12' room with 8' ceilings has 384 sq ft of wall. That is 12 raw sheets, or 14 sheets after waste, with no ceiling included.
• Walls + ceiling, 4x8: the same room with the ceiling (144 sq ft) totals 528 sq ft, about 19 sheets after waste.
• Big open room, 4x12: a 24' x 18' great room with 10' ceilings (walls + ceiling) is about 1,272 sq ft, 30 sheets of 4x12, against 44 sheets of 4x8 for the same room.

What changes the result the most

If you adjust the inputs and watch the count move, a few factors dominate:

• Ceiling on or off: the ceiling adds 37.5% to the wall area of a 12' x 12' room with 8' walls and 48% to the 20' x 15' room with 9' walls.
• Sheet size: moving from 4x8 to 4x12 cuts the sheet count by roughly a third for the same area.
• Ceiling height: a 9' ceiling adds 12.5% more wall area than an 8' one, and a 10' ceiling adds 25%.
• Room shape: long, narrow rooms have more perimeter (and wall area) per square foot of floor than square rooms.
• Waste factor: bumping from 10% to 15% on a complex room adds a few sheets but prevents shortfalls.

Practical tips for buying drywall

• Always order about 10% extra. Offcuts and the occasional cracked sheet are normal; running short means another trip to the store.
• Buy the largest sheet you can handle. Fewer seams mean less taping, less mud and a flatter finish.
• Match thickness to use: 1/2 inch for walls, 5/8 inch Type X for ceilings and garages, moisture-resistant board for bathrooms.
• Stock consumables generously. Mud, tape and screws are cheap relative to the time lost when you run out.
• Store sheets flat and dry before installation so they do not bow or absorb moisture.

Limitations and assumptions

This calculator is a planning estimate, not a precise material order. Keep these assumptions in mind:

• It uses gross wall area and does not subtract doors or windows; that margin is usually consumed by cutting waste.
• It assumes standard rectangular rooms. Vaulted ceilings, soffits, dormers and angled walls need manual adjustment.
• Screw, mud and tape figures follow USG's estimating rates and vary with stud spacing, finish level (Levels 0 to 5) and crew habits.
• It does not include corner bead, primer, paint, adhesive or labor.
• It counts sheets regardless of thickness, so choose the right type (1/2", 5/8" Type X, moisture-resistant) for your application.

Related materials and calculators

Drywall is one layer of a finished room. Once the board is up, you will want a few sister tools:

• To estimate gallons for the finish coat, use the Paint Calculator.
• To size a slab, footing or floor, use the Concrete Calculator.
• For any area in square feet, use the Square Footage Calculator.
• To convert dimensions of any material to volume, use the Cubic Yard Calculator.
• For landscape fill, use the Gravel Calculator and Mulch Calculator.

Sources

• USG: Sheetrock Wallboard Estimator (per 1,000 sq ft: 1,250 screws, 370 ft of tape, 10 gal of ready-mixed compound) and FAQ on joint compound coverage.
• Georgia-Pacific: ToughRock technical guide (fastener spacing, residential ceiling board, installation per GA-216 and ASTM C840).
• Gypsum Association: GA-216 (application and finishing) and GA-214 (levels of finish).
• International Code Council: 2021 International Residential Code, Section R302.6 (dwelling-garage separation).