THE NUMBERS, EXPLAINED
How to use this calculator.
Segments partition one full billing cycle without overlaps or gaps. Daily proration uses the maximum of actual seats and committed minimum.
Start with your inputs
Enter seat counts in successive cycle segments, billable days in each segment, committed minimum seat count, full-cycle seat price (currency), seat subscription amount already invoiced (currency). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Seat counts in successive cycle segments | 10,15,12 |
| Billable days in each segment | 10,10,10 |
| Committed minimum seat count | 10 |
| Full-cycle seat price (currency) | 30 |
| Seat subscription amount already invoiced (currency) | 300 |
A worked example
With the example inputs above, billed seat-days after minimum is 370. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Billed seat-days after minimum | 370 |
| Weighted average billable seats | 12.333333 |
| Final cycle seat charge (currency) | 370 |
| True-up amount (currency) | 70 |
How this is calculated
Billed seat-days after minimum
Apply committed minimum separately to each dated segment.
Weighted average billable seats
Divide billed seat-days by cycle days.
Final cycle seat charge (currency)
Price the day-weighted seat count.
True-up amount (currency)
Subtract the amount already invoiced.
Symbols and units
- a
- Seat counts in successive cycle segments
- b
- Billable days in each segment
- c
- Committed minimum seat count
- d
- Full-cycle seat price (currency)
- e
- Seat subscription amount already invoiced (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
Segments partition one full billing cycle without overlaps or gaps. Daily proration uses the maximum of actual seats and committed minimum.
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?
Billed seat-days after minimum; Weighted average billable seats; Final cycle seat charge (currency); True-up amount (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: Segments partition one full billing cycle without overlaps or gaps. Daily proration uses the maximum of actual seats and committed minimum.
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.
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