THE NUMBERS, EXPLAINED
How to use this calculator.
Full four-sided gusset around a rounded rectangle; follows the entered panel outline. Seam-end overlap adds to length, while long-edge seam allowances add only to width.
Start with your inputs
Enter rounded panel outer width (mm), rounded panel outer height (mm), panel corner radius (mm), gusset seam-end overlap (mm), finished gusset depth (mm), seam allowance along each strip edge (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Rounded panel outer width (mm) | 100 |
| Rounded panel outer height (mm) | 150 |
| Panel corner radius (mm) | 10 |
| Gusset seam-end overlap (mm) | 10 |
| Finished gusset depth (mm) | 30 |
| Seam allowance along each strip edge (mm) | 5 |
A worked example
With the example inputs above, panel perimeter (mm) is 482.831853. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Panel perimeter (mm) | 482.831853 |
| Gusset cut length (mm) | 492.831853 |
| Gusset cut width (mm) | 40 |
How this is calculated
Panel perimeter (mm)
Replace the four sharp corners with four quarter-circle arcs.
Gusset cut length (mm)
Add seam-end overlap to perimeter.
Gusset cut width (mm)
Add seam allowance along both long edges.
Symbols and units
- a
- Rounded panel outer width (mm)
- b
- Rounded panel outer height (mm)
- c
- Panel corner radius (mm)
- d
- Gusset seam-end overlap (mm)
- e
- Finished gusset depth (mm)
- f
- Seam allowance along each strip edge (mm)
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
Full four-sided gusset around a rounded rectangle; follows the entered panel outline. Seam-end overlap adds to length, while long-edge seam allowances add only to width.
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?
Panel perimeter (mm); Gusset cut length (mm); Gusset cut width (mm). 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: Full four-sided gusset around a rounded rectangle; follows the entered panel outline. Seam-end overlap adds to length, while long-edge seam allowances add only to width.
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 Prealgebra 2e — arithmetic and proportions ↗
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.
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