Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Area-only estimate; actual joints, layout, cutout reuse and fire/moisture requirements are not planned.
Example Calculation
- Wall area: 60 m²
- Ceiling area: 20 m²
- Openings deducted: 8 m²
- Sheet width: 1.2 m
- Sheet length: 2.4 m
- Waste allowance: 10 %
Wall area = 60 m²; Ceiling area = 20 m²; Openings deducted = 8 m²; Sheet width = 1.2 m; Sheet length = 2.4 m; Waste allowance = 10 %. Primary result: 28.
Frequently asked questions
How do I use this calculator?
Enter wall area, ceiling area, openings deducted, sheet width, sheet length, waste allowance. The result updates automatically. Use Reset to restore the example values.
What method does it use?
sheets=ceil((walls+ceiling−openings)(1+waste)/(sheet width ×length)).. Area-only estimate; actual joints, layout, cutout reuse and fire/moisture requirements are not planned.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.