THE NUMBERS, EXPLAINED
How to use this calculator.
Compares measured area change in separate test patches. Negative removal indicates a measured increase; area reduction is not proof of fabric safety or removal of invisible residues.
Start with your inputs
Enter before stain areas (cm²), after stain areas (cm²), treatment durations (min). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Before stain areas (cm²) | 10,20 |
| After stain areas (cm²) | 2,5 |
| Treatment durations (min) | 4,5 |
A worked example
With the example inputs above, observed area removal (%) is 80, 75. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Observed area removal (%) | 80, 75 |
| Area removal rate (cm²/min) | 2, 3 |
How this is calculated
Observed area removal (%)
Divide each measured reduction by its starting area.
Area removal rate (cm²/min)
Divide each measured reduction by test duration.
Symbols and units
- a
- Before stain areas (cm²)
- b
- After stain areas (cm²)
- c
- Treatment durations (min)
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
Compares measured area change in separate test patches. Negative removal indicates a measured increase; area reduction is not proof of fabric safety or removal of invisible residues.
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?
Observed area removal (%); Area removal rate (cm²/min). 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: Compares measured area change in separate test patches. Negative removal indicates a measured increase; area reduction is not proof of fabric safety or removal of invisible residues.
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 →