THE NUMBERS, EXPLAINED
How to use this calculator.
Use effective cover dimensions after overlap. Count roof planes separately. This is not a wind-load or fixing specification.
Start with your inputs
Enter roof plane width (m), plane slope length (m), effective sheet cover width (m), effective cover length (m). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Roof plane width (m) | 10 |
| Plane slope length (m) | 4 |
| Effective sheet cover width (m) | 1 |
| Effective cover length (m) | 2 |
A worked example
With the example inputs above, sheets is 20. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Sheets | 20 |
How this is calculated
Sheets
roundUp(a ÷ c) × roundUp(b ÷ d)
Symbols and units
- a
- Roof plane width (m)
- b
- Plane slope length (m)
- c
- Effective sheet cover width (m)
- d
- Effective cover length (m)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
roundUp(x) rounds up to the next whole number. Values within two floating-point rounding units of an integer are treated as that integer.
Assumptions and limits
Use effective cover dimensions after overlap. Count roof planes separately. This is not a wind-load or fixing specification.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Sheets. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Use effective cover dimensions after overlap. Count roof planes separately. This is not a wind-load or fixing specification.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →