THE NUMBERS, EXPLAINED
How to use this calculator.
Divide each recording by its playback speed, then add the allowance as a percentage of accelerated viewing time. One speed is required per recording.
Start with your inputs
Enter recording lengths (minutes), playback speeds, pause and note allowance (%). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Recording lengths (minutes) | 60,90 |
| Playback speeds | 1.5,2 |
| Pause and note allowance (%) | 20 |
A worked example
With the example inputs above, viewing time before pauses (minutes) is 85. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Viewing time before pauses (minutes) | 85 |
| Study time including pauses (minutes) | 102 |
| Study time by recording (minutes) | 48, 54 |
How this is calculated
Viewing time before pauses (minutes)
Sum each recording length divided by its matching playback speed.
Study time including pauses (minutes)
Viewing time × (1+c/100).
Study time by recording (minutes)
For each recording: length / speed × (1+c/100).
Symbols and units
- a
- Recording lengths (minutes)
- b
- Playback speeds
- c
- Pause and note allowance (%)
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 recording by its playback speed, then add the allowance as a percentage of accelerated viewing time. One speed is required per recording.
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?
Viewing time before pauses (minutes); Study time including pauses (minutes); Study time by recording (minutes). 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 recording by its playback speed, then add the allowance as a percentage of accelerated viewing time. One speed is required per recording.
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.
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