Drywall Calculator

Sheets, screws, joint compound, and tape for walls and ceilings. Updated for 2026.

Last reviewed July 2026 · Free · Nothing you enter is stored

How this calculator works

Sheet count = area ÷ sheet size, plus 10% waste, rounded up. Fasteners use the rule of one screw per square foot (32 per 4×8 sheet at 16" o.c. framing). Joint compound runs about 0.053 lb per sq ft (a 4.5-gal bucket of all-purpose mud handles roughly 450–500 sq ft) and tape about 0.37 linear ft per sq ft of board.

The waste allowance

This calculator adds 10% to the raw area before it divides that area into sheets. Almost all of that allowance is offcut you will never use again: the narrow strip left beside a door, the corner piece too short to land on two studs, the sheet that gets a broken corner coming up a stairwell. It is also the reason the calculator does not subtract standard windows and doors from your total. The board cut out of those openings mostly becomes scrap, so deducting the openings and then adding waste on top of that leaves you short. Coming up one sheet shy late in the day means a second trip, and often a butt joint in the middle of a wall that did not need to be there.

Sheet size, and the joints you avoid

Gypsum board comes four feet wide in eight, ten and twelve foot lengths, which is 32, 40 and 48 square feet per sheet. The arithmetic of sheet count is simple enough, and a twelve foot sheet covers half again what an eight foot sheet does, so the count drops by about a third when you move up.

The reason to reach for the longer board is not the sheet count, though. It is the joints. The long edges of a sheet are tapered from the factory, so tape and compound sit in a shallow recess and finish nearly flat. The cut ends are not tapered, and where two ends meet you get a butt joint: a seam with no recess at all, which has to be floated eight to twelve inches wide on each side to disappear under paint. Longer sheets mean fewer butt joints, and butt joints are the hardest thing in the room to finish invisibly.

The trade-off is handling. A four by eight sheet can be carried and lifted by one person with some effort. Twelve foot sheets want two people, a clear path, and a room that will actually accept a twelve foot board without a bend in the hallway. On a ceiling they are worth arranging help for; in a tight remodel with a switchback stair they often are not.

Fastening is a spacing rule, not a screw count

USG's installation guidance for Sheetrock brand panels sets fastener spacing rather than a number of screws per board. In the field of the sheet, the maximum is twelve inches on centre on ceilings and sixteen inches on walls. Around the perimeter the spacing tightens to seven inches on ceilings and eight inches on walls, because the edges are where the board is least supported and where a loose panel shows first.

A screw count falls out of that spacing once you know the framing layout, which is why there is no manufacturer figure for screws per sheet. A four by eight sheet hung on sixteen inch centres typically works out at around thirty-two screws. Move to twenty-four inch centres, hang the sheet the other way round, or use adhesive with reduced fastening and the number changes. Treat any per-sheet figure as derived from your own framing, not as a specification.

One rule is absolute regardless of spacing. Fasteners must sit at least three-eighths of an inch in from the edges and ends of the board. Closer than that and the screw head tears through the paper facing, which is the layer actually carrying the load. A fastener that has torn out is holding almost nothing, and it will telegraph through the finished joint later.

Joint compound and the number of coats

Compound estimates land at roughly ten to twelve gallons per 1,000 square feet of finished board, which works out at about 83 to 100 square feet per gallon. That figure describes topping compound in a finished multi-coat system, and it is a planning number rather than a promise.

What actually drives consumption is the number of coats. A standard finish is three: a bedding coat that sets the tape, a fill coat, and a finish coat, each one applied thinner and feathered wider than the last. Butt joints take more compound than tapered seams because they have to be built out across a wider band, and inside corners and fastener heads add their own share. A wall with a lot of short runs and openings uses more mud per square foot than a long uninterrupted one.

Because of that variability, it is sensible to buy slightly over rather than exactly to the estimate. Unopened compound keeps for months, and running out halfway through a coat is worse than a leftover bucket. Stopping mid-wall leaves a lap line in the middle of a seam that has to be sanded out before the next coat goes on.

Where code chooses the board for you

Most of a house is a free choice between half inch and five-eighths board, decided by span, framing spacing and how much you care about sound. The garage is not a free choice. The IRC's garage separation provisions require five-eighths inch Type X gypsum board on a garage ceiling where there is habitable space above it.

The walls between the garage and the residence, and the structure supporting that separation, require a minimum of half inch gypsum board. That includes posts and columns carrying the floor-ceiling assembly above, which are easy to overlook once the walls are sheeted and the framing is out of sight.

The common residential mistake is to buy half inch board for the whole garage and miss the ceiling requirement entirely. It is an expensive thing to correct after taping, and it is the sort of item an inspector looks for specifically. Five-eighths board is also noticeably heavier, so a garage ceiling in Type X is a job to plan help or a panel lift around. Local amendments vary, so confirm with your building department before you order.

Fastener spacing and edge distance

Maximum spacings for screw attachment of gypsum panels to wood framing. Screws per sheet are derived from these spacings and your framing layout, not published as a flat figure.

Fastener spacing and minimum edge distance from USG's installation guidance for Sheetrock brand gypsum panels. Screws per sheet is derived arithmetic, not a manufacturer specification.

What goes wrong hanging board

Screws driven too close to the edge. Three-eighths of an inch is the minimum from any edge or end. Closer and the head tears out the paper, leaving a fastener that holds very little and shows through the joint later.

Half inch board on a garage ceiling. Where habitable space sits above a garage, the ceiling requires five-eighths inch Type X. Half inch is the minimum for the separating walls and supporting structure, not the ceiling.

Using wall spacing on a ceiling. Ceilings are fastened tighter, twelve inches in the field and seven at the perimeter, because the panel is loaded by its own weight the whole time.

Defaulting to eight foot sheets everywhere. Short sheets on a long wall create butt joints, which have no factory taper and must be floated wide to disappear. Longer boards trade carrying effort for far less finishing.

Ordering compound to the exact estimate. Coverage of about 83 to 100 square feet per gallon assumes a normal three coat system. Wide butt joints, extra coats and a room full of openings all push consumption up.

Frequently asked questions

Why your state changes the price (but not the quantity)

How much drywall you need is physics — it doesn't care where you live. What it costs does. Labor rates, delivery distance, fuel, and local demand move installed prices by roughly 45 points from end to end: Arkansas, Mississippi, North Carolina sit near the bottom of the range, while Alaska, Hawaii, New York sit at the top. The Price this for selector at the top of the calculator applies a published construction cost index for your state to the 2026 national averages, so the dollar figures move and the material list stays put.

Treat the result as a budgeting range, not a quote. Two metros inside the same state can differ by more than the statewide index suggests, and a single busy contractor can outweigh both. See the full cost index for all 50 states and where the price data comes from.