Drywall Calculator
Enter the room, choose whether the ceiling gets rocked, subtract the openings, and get a sheet count for 4x8, 4x10, or 4x12 board — waste applied to the area first, then rounded up to whole sheets.
Room and sheet size
Example: a 12 × 10 × 8 ft room with ceiling, 40 sq ft of openings, 10% waste → 15 sheets of 4x8.
Sheet counts are for shopping, not construction judgment — fire ratings, structural questions, and permits belong with a licensed professional or your code office.
Walls, ceiling, waste, sheets — in that order
walls = 2 × (length + width) × height; the ceiling, when included, adds
length × width. The worked room: 352 sq ft of walls + 120 sq ft of ceiling − 40 sq ft of openings = 432 sq ft.
Waste lifts it to 475.2 sq ft, and dividing by the 32 sq ft
face of a 4x8 sheet gives 15 sheets with 4.8 sq ft to spare. Computed by the engine at build time — the same one wired to the form.
Frequently asked questions
Which sheet size should I pick?
The one you can physically handle and haul: 4x8 sheets (32 sq ft) are the DIY standard, while 4x10 and 4x12 mean fewer joints to tape but need two sets of hands and a clear stairwell. The count updates instantly when you switch sizes, so compare all three.
Do I subtract every door and window?
Hangers usually subtract large openings and ignore small ones, because the cutout over a window often becomes unusable scrap anyway. This tool subtracts exactly what you enter — leaving small openings in simply adds a little natural margin.
What does the waste percentage cover?
Cuts that land off-stud, breakage, the strip lost when a sheet is trimmed to a sloped or out-of-square wall. Around 10% is the common convention for simple rooms; closets and angled ceilings chew through more.
Does the estimate include screws, tape, and mud?
No — this page counts board only. Fastener and finishing quantities follow different rules (per-sheet and per-joint conventions), and mixing them into one number would blur what you are actually buying.
Room dimensions are processed locally and never leave your device. The shared estimation pipeline is documented on the methodology page.