Wallboard material calculator
Drywall calculator
Estimate drywall sheets for identical rectangular walls using net area, editable sheet dimensions, nominal opening deductions, and waste.
Drywall estimator
Enter wall and sheet details
Results update as soon as every value is valid.
Estimated requirement
Sheets needed
4 whole sheets are estimated from a waste-adjusted exact count of 3.67.
- Gross wall area
- 9.6 m²
- Door deduction
- 0 m²
- Window deduction
- 0 m²
- Total opening deduction
- 0 m²
- Net drywall area
- 9.6 m²
- Sheet dimensions
- 1.2 × 2.4 m
- Sheet area
- 2.88 m²
- Exact count before waste
- 3.33
- Waste allowance
- 10%
4 whole sheets are estimated from a waste-adjusted exact count of 3.67.
Estimating limits
Assumptions
- All entered walls are identical rectangles; ceilings are excluded.
- Each door deducts 1.9 m² and each window deducts 1.5 m².
- The estimate divides net area by sheet area; it does not optimize physical layout.
- Whole sheets round upward. Seams, orientation, offcuts, damage, staggered joints, complex shapes, and installer practice can increase use.
- Finishing materials, framing, insulation, and fixings are excluded.
Confirm project requirements and locally applicable construction practices. See the shared calculation methodology.
Transparent method
Formula and method
Gross area = wall length × wall height × number of walls
Net area = gross area − nominal door and window deductions
Base exact sheets = net area ÷ sheet area
Whole sheets = ceiling(base exact sheets × (1 + waste ÷ 100))
Square metres are canonical. If nominal opening deductions equal or exceed gross wall area, the calculator reports an error instead of a sheet estimate.
Verified example
One 4 m × 2.4 m wall
With no openings, gross and net area are 9.60 m². Using 1.2 m × 2.4 m sheets gives 3.33 exact sheets; 10% waste gives 3.67, rounded to 4 whole sheets.
Common questions
Drywall calculator FAQ
Why can actual sheet use exceed the estimate?
Area division does not optimize seams, orientation, cuts, offcuts, damage, or staggered joints.
Why are sheets rounded up?
Partial sheets cannot be purchased, so the final estimate rounds upward.
Are doors and windows deducted?
Yes. Counts use fixed nominal deductions of 1.9 m² per door and 1.5 m² per window.
Does it calculate ceilings?
No. It covers identical rectangular wall surfaces only.
Does it optimize sheet orientation or cuts?
No. This is an area-based material estimate, not a layout plan.
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