THE NUMBERS, EXPLAINED
How to use this calculator.
All distances are measured from the same garment top datum. Cutting opens/removes the existing hem; new cut line must lie within current finished length.
Start with your inputs
Enter current finished length (cm), desired finished length (cm), new hem allowance (cm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Current finished length (cm) | 100 |
| Desired finished length (cm) | 90 |
| New hem allowance (cm) | 3 |
A worked example
With the example inputs above, shortening at finished edge (cm) is 10. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Shortening at finished edge (cm) | 10 |
| New cut line from top (cm) | 93 |
| Distance above current edge to cut (cm) | 7 |
How this is calculated
Shortening at finished edge (cm)
Subtract desired finished length from current length.
New cut line from top (cm)
Add the new hem allowance to desired finished length.
Distance above current edge to cut (cm)
Subtract the proposed cut-line position from current finished length.
Symbols and units
- a
- Current finished length (cm)
- b
- Desired finished length (cm)
- c
- New hem allowance (cm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
All distances are measured from the same garment top datum. Cutting opens/removes the existing hem; new cut line must lie within current finished length.
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?
Shortening at finished edge (cm); New cut line from top (cm); Distance above current edge to cut (cm). 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: All distances are measured from the same garment top datum. Cutting opens/removes the existing hem; new cut line must lie within current finished length.
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.
Further reading
OpenStax: Solve proportions and their applications ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
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 →