THE NUMBERS, EXPLAINED
How to use this calculator.
The entered chargeability counts embody the supplied cancellation policy. Dates can be grouped into mutually exclusive rate bands.
Start with your inputs
Enter scheduled lesson counts by rate band, canceled lesson counts by rate band, chargeable cancellation counts by band, lesson prices by band (currency), payments already received (currency). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Scheduled lesson counts by rate band | 4,3 |
| Canceled lesson counts by rate band | 1,1 |
| Chargeable cancellation counts by band | 1,0 |
| Lesson prices by band (currency) | 30,40 |
| Payments already received (currency) | 50 |
A worked example
With the example inputs above, billable lessons by band is 4, 2. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Billable lessons by band | 4, 2 |
| Invoice total (currency) | 200 |
| Outstanding balance (currency) | 150 |
How this is calculated
Billable lessons by band
Subtract cancellations then restore those chargeable under the supplied policy.
Invoice total (currency)
Multiply billable lessons by each rate.
Outstanding balance (currency)
Subtract receipts from the invoice total.
Symbols and units
- a
- Scheduled lesson counts by rate band
- b
- Canceled lesson counts by rate band
- c
- Chargeable cancellation counts by band
- d
- Lesson prices by band (currency)
- e
- Payments already received (currency)
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
The entered chargeability counts embody the supplied cancellation policy. Dates can be grouped into mutually exclusive rate bands.
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?
Billable lessons by band; Invoice total (currency); Outstanding balance (currency). 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: The entered chargeability counts embody the supplied cancellation policy. Dates can be grouped into mutually exclusive rate bands.
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: Describe and Identify Cost Drivers ↗
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 →