Drywall Calculator: measuring notes and method
Separate walls, ceilings and board types
Keep ceiling board, wet-area board and ordinary wall board as different project items even when their sheet dimensions match.
Check the sheet layout
Openings can reduce area without saving a whole sheet. Sketch sheet positions and joints before ordering; a cutout from a door may not be reusable elsewhere. Keep framing, screws, tape and compound separate.
CHECK A PRACTICAL EXAMPLE
The Nowra walls: before and after an allowance
The recorded net wall area is 44 m². The selected sheets are 3 × 1.2 m. These are reconstructed area estimates, not purchase records.
No cutting allowance
- Sheets to buy
- 13
- Net area
- 44 m²
10% area allowance
- Sheets to buy
- 14
- Net area
- 44 m²
The 18 m² ceiling is a separate item. Openings and offcuts do not necessarily save whole sheets; the sheet layout determines whether the area estimate is sufficient.
Fixed comparison in metric units. Values are illustrative unless linked to a recorded project; changing the calculator above does not change this example.
Formula
Sheets = (area − openings) × (1 + waste ÷ 100) ÷ (sheet length × sheet width), rounded up.
Product reference: USG material estimator
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Openings / excluded area
- 0 m²
- Sheet length
- 2.4 m
- Sheet width
- 1.2 m
- Waste allowance
- 10 %
Sheets to buy: 10
Imperial worked example
- Total surface area
- 258.3339 ft²
- Openings / excluded area
- 0 ft²
- Sheet length
- 7.874 ft
- Sheet width
- 3.937 ft
- Waste allowance
- 10 %
Sheets to buy: 10
Follow the calculation
Lengths in this working are in metres.
- Net area = 24 − 0 = 24 m².
- Area per sheet = 2.4 × 1.2 = 2.88 m².
- Sheets = 24 × 1.1 ÷ 2.88, rounded up. Check the cutting layout separately.
Reviewed 19 October 2026. How calculations are checked · Report a correction