How to use this calculator
Drywall quantity is wall area plus ceiling area (if you include it), minus the openings you choose to deduct, times layers, plus waste — then rounded up to whole sheets. Keeping walls and ceilings separate matters, because a ceiling is often a different thickness and is hung differently.
Enter your own figures in the form above. A blank field is treated as missing — not as zero — so the tool will ask you to complete it. A genuine zero is accepted where it makes sense (for example, no HOA dues). Press Calculate for a breakdown, Load worked example to fill in the example below, or Reset to return to the defaults.
Formula and assumptions
Wall area = 2 × (length + width) × height. Ceiling area (if included) = length × width. Net area = (walls + ceiling) − openings. Required area = net × layers × (1 + waste %). Sheets = required ÷ sheet area, rounded UP. Purchased area = sheets × sheet area.
Worked example
Worked example: 12 × 10 ft room, 8 ft walls, openings 32 ft², 4 × 8 sheets, 10% waste, 1 layer, walls only. Gross walls 352 ft²; net 320 ft²; required 352 ft²; 11 sheets.
Use the Load worked example button above to reproduce this example in the form, then change one input at a time to see what drives the result.
Limitations and common mistakes
A quantity estimate is not a cut layout: sheet orientation, stud spacing, offcuts and small openings do not always reuse cleanly. Do not automatically deduct tiny openings as if every scrap were reusable. Thickness, fire rating and moisture resistance are product selections outside this tool.
Frequently asked questions
Should I deduct every door and window?
Deduct openings you can measure confidently. Very small openings are sometimes left in, because cutting around them wastes more than the opening saves.
Why do layers matter?
A second layer doubles material (and fasteners and finishing). Enter layers explicitly rather than doubling the waste figure.
What about closets and soffits?
Measure them as separate rectangles and add their area to the room area in your own notes, or run the tool once per space.
Sources
No external price, product or market data is used on this page. Every price, density, coverage and rate is a figure you enter, or a clearly labelled illustrative default in the form. Check product labels and supplier quotes for the figures that apply to your job.
Estimates only. Results from this calculator are not a loan offer, appraisal, engineering design, equipment selection or contractor quote.