Drywall calculator

Every dimension must be a finite positive number: zero or negative wall length, ceiling height, or sheet size is rejected as invalid_input instead of a hollow zero. Use it free in the browser before you order, or call the API at $0.002 per successful request when estimating software needs a reproducible sheet count.

How wall lengths become a sheet count

Gypsum board is sold as whole rectangular sheets, so a take-off starts from the hanging surface and ends on an integer board count. A rectangular 5 m by 4 m room is [5, 4, 5, 4]; an L-shaped room or a closet partition is simply more numbers in the same list. Ceiling height is the wall height in the same length unit. Openings, waste, screws, joint tape, and mud are out of scope so the page stays a sheet-and-area calculator: subtract doors and windows yourself if you want a net figure, then apply your own cut-and-breakage margin on top of sheets. This calculator treats the room as a list of wall lengths rather than a single precomputed area: you walk the walls, record each run, and send wall_lengths as an array. The engine forms sum_of_lengths as the sum of that list, then total_area as sum_of_lengths times ceiling_height. Sheet area is sheet_length times sheet_width. The exact sheet count is total_area divided by sheet_area; the purchase count sheets is the ceiling of that quotient, so 15.01 boards becomes 16. Hanging boards horizontally or vertically does not change the area identity, and neither does a 4×8 ft versus 4×12 ft choice except through the sheet_length and sheet_width you send. The same identity is used on clipboards, in estimating notebooks, and in this API, so a four-wall room of 5 m and 4 m sides at 2.4 m height with 2.4 m by 1.2 m boards always produces 15 sheets and 43.2 square units of total area when the inputs stay in one unit system.

Input contract, units, defaults, and error behaviour

There is no default board size: a 2.4×1.2 m sheet and an 8×4 ft sheet are different products, and mixing metres of wall with feet of board would silently inflate or shrink the count. Failed validation is not billed. POST a JSON body with four required fields. wall_lengths is an array of finite strictly positive numbers (aliases walls, lengths, wall_length) with at least one entry and at most 100 walls; a comma-separated string of lengths is also accepted. ceiling_height is the wall height in the same length unit (aliases height, h, wall_height) and must be a finite strictly positive number. sheet_length and sheet_width are the board dimensions in that same unit (aliases length, board_length, panel_length and width, board_width, panel_width) and must each be strictly positive. Missing fields, empty strings, empty arrays, non-finite values, and magnitudes above the supported ceiling fail with invalid_input naming the field. A zero or negative dimension fails with a message that the named wall_lengths entry, ceiling_height, sheet_length, or sheet_width must be a positive number, matching the rule that a wall with no extent cannot consume boards. On success the body echoes the parsed wall_lengths, wall_count, sum_of_lengths, ceiling_height, total_area, sheet_length, sheet_width, sheet_area, the exact unrounded sheets_exact, the whole-sheet purchase count sheets, and a short formula string for audit. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline; nothing is stored after the response returns, and the work never leaves your isolate for a model or a network hop.

Where a drywall sheet calculator earns its keep

This is not a screw count from sheets, not a joint-tape roll count from linear seams, and not a paint-quantity take-off from the same walls: those are different search intents with different inputs. On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — lets you move from a phone check at the merchant to an automated pipeline without changing the mathematical result.