THE NUMBERS, EXPLAINED
How to use this calculator.
Divide each finished dimension by its retained fraction. Shrinkage is measured relative to the original dimension; test your own fabric. Seam allowances must already be included in the desired finished dimensions.
Start with your inputs
Enter finished width (cm), finished length (cm), width shrinkage (%), length shrinkage (%). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Finished width (cm) | 90 |
| Finished length (cm) | 180 |
| Width shrinkage (%) | 10 |
| Length shrinkage (%) | 10 |
A worked example
With the example inputs above, cut width (cm) is 100. Change the inputs to explore your own scenario.
Putting the example numbers into the formula
Cut width (cm)
(90) ÷ (1-(10) ÷ 100) = 100
Cut length (cm)
(180) ÷ (1-(10) ÷ 100) = 200
| Result | Example answer |
|---|---|
| Cut width (cm) | 100 |
| Cut length (cm) | 200 |
How this is calculated
Cut width (cm)
a ÷ (1-c ÷ 100)
Cut length (cm)
b ÷ (1-d ÷ 100)
Symbols and units
- a
- Finished width (cm)
- b
- Finished length (cm)
- c
- Width shrinkage (%)
- d
- Length shrinkage (%)
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
Divide each finished dimension by its retained fraction. Shrinkage is measured relative to the original dimension; test your own fabric. Seam allowances must already be included in the desired finished dimensions.
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?
Cut width (cm); Cut length (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: Divide each finished dimension by its retained fraction. Shrinkage is measured relative to the original dimension; test your own fabric. Seam allowances must already be included in the desired finished dimensions.
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: algebra and proportional reasoning ↗
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 →