THE NUMBERS, EXPLAINED
How to use this calculator.
Remaining forecast excludes all committed costs to avoid double counting. Margin values are before unlisted overhead and tax.
Start with your inputs
Enter original contract revenue (currency), original estimated cost (currency), approved revenue changes (currency), costs already committed (currency), uncommitted remaining forecast cost (currency). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Original contract revenue (currency) | 20000 |
| Original estimated cost (currency) | 15000 |
| Approved revenue changes (currency) | 2000 |
| Costs already committed (currency) | 12000 |
| Uncommitted remaining forecast cost (currency) | 7000 |
A worked example
With the example inputs above, original estimated margin (currency) is 5,000. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Original estimated margin (currency) | 5,000 |
| Current forecast margin (currency) | 3,000 |
| Margin erosion (currency) | 2,000 |
| Forecast cost over original estimate (currency) | 4,000 |
How this is calculated
Original estimated margin (currency)
Subtract original expected cost from original revenue.
Current forecast margin (currency)
Deduct committed and additional remaining costs from revised revenue.
Margin erosion (currency)
Compare original and current forecast margins.
Forecast cost over original estimate (currency)
Isolate cost growth before approved revenue changes.
Symbols and units
- a
- Original contract revenue (currency)
- b
- Original estimated cost (currency)
- c
- Approved revenue changes (currency)
- d
- Costs already committed (currency)
- e
- Uncommitted remaining forecast cost (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
Remaining forecast excludes all committed costs to avoid double counting. Margin values are before unlisted overhead and tax.
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?
Original estimated margin (currency); Current forecast margin (currency); Margin erosion (currency); Forecast cost over original estimate (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: Remaining forecast excludes all committed costs to avoid double counting. Margin values are before unlisted overhead and tax.
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 →