Calculators
Drywall measuring and waste calculators
Wall and ceiling areas, waste factors, sheet weights, thickness and orientation choices, vaulted ceilings and patch sizing.
Every drywall estimate starts with an area, and most estimating mistakes start there too: a ceiling counted twice, a sloped ceiling measured flat, a closet forgotten, a door subtracted at the slab size instead of the opening. These calculators take rooms as length, width and height, subtract openings at their rough sizes, handle L-shapes and slopes, and hand the net area to the sheet calculators.
The group also answers the choices that come before the first cut: how much waste to allow for a cut-up room, 1/2 in or 5/8 in board, horizontal or vertical sheets, and what the stack on the trailer will weigh.
9 calculators
Wall Area Calculator
Gross and net area of up to six walls, sloped tops included, with doors and windows taken out at their real sizes.
Ceiling Area Calculator
Ceiling area and perimeter for a rectangle, an L-shape or several rooms, with skylights and hatches taken out.
Vaulted & Sloped Ceiling Area Calculator
True area of a cathedral or shed ceiling from the pitch or the heights, with the gable triangles and the sheets.
Drywall Waste Factor Calculator
A waste allowance built from what forces cuts in your room: shape, openings, wall height, sheet length and slopes.
Drywall Sheet Weight Calculator
Weight per sheet and for the order by size and board type, the trips in your vehicle and the load on the floor.
Drywall Thickness Selector
The board thickness and type for a wall or ceiling from the framing, fire, moisture, sound and use, with the code reason for each.
Sheet Orientation Calculator
Horizontal or vertical on one wall: sheets, tapered joints and butt joints both ways, and which to choose.
Drywall Repair Patch Calculator
The right repair for a hole by its size, from spackle to a mesh patch to a new section, with the materials to buy.
Square Feet to Sheets Converter
Turn an area into sheets of any size with waste, plus the screws, compound and tape that go with them.
Guides for this topic
Drywall repairs: patch kits, California patches, or a new section
The size of the hole decides the repair. A nail hole takes a fingertip of spackle; a fist hole takes a patch; a water-stained ceiling takes a saw.
4×8, 4×12 and the rest: sheet sizes, orientation and seams
The size and direction of the sheets decide how many joints there are to tape, and joints are where the labour and the visible flaws are. Here is how to choose.
Drywall thickness: 1/4, 3/8, 1/2, 5/8 and type X
Half-inch board covers most walls in most homes. The exceptions are ceilings on wide framing, fire separations, curves and sound walls, and each has a rule.
What drywall weighs and how to get it into the house
A room's worth of drywall weighs as much as a small car. Planning how it travels, where it is stacked and how it goes up saves backs, floors and corners.
Garage drywall: the fire-separation rules and type X
An attached garage is the one place most houses need fire-rated drywall. The rules are short and specific, and they decide which board goes on which surface.
How many sheets of drywall do I need? The complete method
Square feet divided by 32 is where most counts start and where most go wrong. Here is the method a careful estimator follows, step by step, on a real room.
Removing old drywall and plaster: weight, dumpsters and asbestos
Tear-outs are quick and heavy. The planning is mostly about weight, and, in older homes, one test before the first swing.
Questions people ask
- How do I measure walls for drywall?
- Measure the length of each wall and the ceiling height, multiply, and add the walls together, or take the room perimeter times the height. Subtract each door and window at its rough opening, about 20 sq ft for a standard door and 15 sq ft for a 3 × 5 ft window. Do not subtract small openings such as outlets, and do not subtract an opening you will drywall into, like a closet.
- What waste percentage should I use for drywall?
- Allow 10% for a plain rectangular room with few openings, 15% for rooms with angles, closets and many windows, and 20% for sloped ceilings, dormers and small cut-up spaces. Waste is lower with sheet sizes that match the wall length, and higher when every sheet needs a cut at a window or an outlet.
- How much does a sheet of drywall weigh?
- A 4 × 8 sheet of standard 1/2 in board weighs about 51 lb (1.6 lb per sq ft); the lightweight versions are about 40 lb (1.25 lb per sq ft). A 4 × 8 sheet of 5/8 in type X is about 70 lb, and a 4 × 12 sheet of 5/8 in is over 100 lb, which is why ceilings get a lift or two people.
- 1/2 in or 5/8 in drywall?
- Half-inch board is the standard for walls on 16 in framing and ceilings on 16 in joists. Use 5/8 in for ceilings on 24 in joists, where a fire rating is required (attached garages, furnace rooms, between units), where you want more sound mass, and on walls that take abuse. Quarter and 3/8 in board are for curved walls and for covering old walls.
- Should drywall be hung horizontally or vertically?
- Horizontally on walls up to about 9 ft 1 in tall: two sheets stacked cover an 8 ft wall with one long tapered joint at a comfortable height and fewer linear feet of joint than vertical sheets. Vertically when the wall is taller than two sheet widths, on steel studs in commercial work, or where a fire-rated assembly specifies it.
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