Drywall Calculator
Calculate how many drywall sheets you need, with a waste allowance.
Assumptions used in this calculation
- Waste covers cutouts: The waste percentage is assumed to cover offcuts from door, window, and electrical box cutouts, if you already subtracted openings from wall area, a lower waste percentage may suffice.
- Full sheets only: Counts whole sheets needed, it doesn't try to optimize layout to reuse offcuts across different wall sections.
About this calculator
Drywall sheets come in fixed sizes, most commonly 4×8 or 4×12 feet, and a room's actual wall area rarely divides evenly into those dimensions, leaving offcuts around doors, windows, corners and electrical boxes that need to be planned for before ordering. This calculator adds your chosen waste percentage to the total wall area, divides that inflated figure by the area of one sheet (sheet width times height), and rounds up to a whole sheet count since drywall can't be bought in fractional sheets. Enter wall area, sheet dimensions and a waste percentage, and it returns exactly how many sheets to order instead of you estimating cutoffs by eye and risking a mid-installation shortage. Because the waste allowance is meant to absorb cutout losses, if you've already subtracted door and window openings from your wall area figure, a smaller waste percentage than the 10% default may be sufficient.
Worked example
800 sqft, 4x8ft sheets, 10% waste
Result: 28 sheets
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