THE NUMBERS, EXPLAINED
How to use this calculator.
This is a total-length estimate. A cutting plan may need more stock for individual long runs.
Start with your inputs
Enter room perimeter (m), door openings (m), stock length (m), waste (%). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Room perimeter (m) | 20 |
| Door openings (m) | 2 |
| Stock length (m) | 3 |
| Waste (%) | 10 |
A worked example
With the example inputs above, stock lengths is 7. Change the inputs to explore your own scenario.
Putting the example numbers into the formula
Net run (m)
(20)-(2) = 18
| Result | Example answer |
|---|---|
| Stock lengths | 7 |
| Net run (m) | 18 |
How this is calculated
Stock lengths
roundUp((a-b) × (1+d ÷ 100) ÷ c)
Net run (m)
a-b
Symbols and units
- a
- Room perimeter (m)
- b
- Door openings (m)
- c
- Stock length (m)
- d
- Waste (%)
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
This is a total-length estimate. A cutting plan may need more stock for individual long runs.
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?
Stock lengths; Net run (m). 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: This is a total-length estimate. A cutting plan may need more stock for individual long runs.
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 →