Forecast spot instances spend over a multi-month period using active units, monthly usage, unit-hour pricing, workload growth, and cost overhead. The calculator compounds workload changes month by month and shows the full-period cost, average monthly cost, and the first-to-last-month movement. Use it for budgeting and scenario planning rather than as a provider invoice.
The main result is the cumulative modeled compute spend across the selected period. The secondary results reveal whether a reasonable total is hiding a steep end-of-period run rate.
Prices and coverage rules vary by provider and contract. Enter your effective rate and known overhead rather than assuming a universal discount.
With 20 units, 500 hours, $0.12 per unit-hour, 12 months, 2% monthly growth, and 5% overhead, the first month is $1,260.00 and the 12-month total is $16,899.23.
Yes. Each month applies the entered growth rate to the preceding month’s workload.
It adds a percentage to modeled compute cost for fees or related overhead; it does not rewrite the base rate.
Every month uses the same workload, so total cost equals first-month cost multiplied by the forecast length.
Yes. Enter a negative monthly growth rate greater than -100%.
Only if you represent them with the overhead input; verify final charges with your provider.
| Variable | Meaning |
|---|---|
| Units | Average concurrently active billable units |
| Hours | Monthly billable hours per unit, maximum 744 |
| Growth | Monthly workload change compounded by month |
| Overhead | Additional percentage applied to compute cost |