Cloud Budget Forecast Calculator
Project the rest of the year from spend to date, month-on-month growth and a new workload, then test it against the budget.
About Cloud Budget Forecast Calculator
A naive forecast multiplies the last month by twelve, which ignores both compounding growth and anything you already know is coming. This model compounds the latest run rate month by month, applies committed savings as a flat reduction and adds the new workload only from the month it actually lands, so the shape of the curve reflects real plans. Budget conversations happen once a quarter but the overrun builds every month, and a forecast that shows the exhaustion month gives you the lead time to change something. Forecasts inherit every assumption you feed them — treat this as a planning aid rather than a committed financial projection.
Formula
Cloud Budget Forecast
forecast = spend to date + Σ over remaining months of (latest month × (1 + growth)^m × (1 − committed savings) + new workload once it starts).
- growth
- Compounding month-on-month growth rate taken from the trailing average
- m
- Index of each remaining month in the year
- committed savings
- Reduction from optimisation work that is already agreed and funded
Worked example
With the default values below, Cloud Budget Forecast Calculator returns Forecast Full-Year Spend of $2,561,487.24. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Spend so far this yearaccepts 0–500,000,000 USD
- 700,000 USD
- Months already billedaccepts 1–11 months
- 4 months
- Latest full month of spendaccepts 0–50,000,000 USD/month
- 190,000 USD/month
- Month-on-month growthaccepts -20–30 %
- 4 %
- New workload landing later in the yearaccepts 0–20,000,000 USD/month
- 25,000 USD/month
- Month the new workload startsaccepts 1–12 month of year
- 7 month of year
- Savings actions already committedaccepts 0–60 %
- 6 %
- Annual budgetaccepts 0–500,000,000 USD/year
- 2,600,000 USD/year
Results
- Forecast Full-Year Spend
- $2,561,487.24
- Forecast Over the Budget
- -$38,512.76
- Forecast Against Budget
- 98.5%
- Month the Budget Runs Out
- 12.2 month of year
- Average Forecast Month Remaining
- $232,685.91
- Naive Annualised Run Rate
- $2,280,000.00
- Budget Outlook
- The forecast lands inside budget with very little slack
Step by step
- 1Values used
- 2Cloud Budget Forecast
- 3Forecast Full-Year Spend= 2,561,487.24
- 4Forecast Over the Budget= -38,512.76
- 5Forecast Against Budget= 98.5
- 6Month the Budget Runs Out= 12.2 month of year
- 7Average Forecast Month Remaining= 232,685.91
- 8Naive Annualised Run Rate= 2,280,000.00
Assumptions and limits
- The result is derived only from the 8 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation or tax into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Cloud Budget Forecast calculated?
forecast = spend to date + Σ over remaining months of (latest month × (1 + growth)^m × (1 − committed savings) + new workload once it starts). A naive forecast multiplies the last month by twelve, which ignores both compounding growth and anything you already know is coming. This model compounds the latest run rate month by month, applies committed savings as a flat reduction and adds the new workload only from the month it actually lands, so the shape of the curve reflects real plans.
Why does Cloud Budget Forecast matter?
Budget conversations happen once a quarter but the overrun builds every month, and a forecast that shows the exhaustion month gives you the lead time to change something. Forecasts inherit every assumption you feed them — treat this as a planning aid rather than a committed financial projection.
What values do I need to enter?
This calculator takes 8 inputs: Spend so far this year, Months already billed, Latest full month of spend, Month-on-month growth, New workload landing later in the year, Month the new workload starts, Savings actions already committed, Annual budget. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
Why is compounding growth worse than it looks?
Four percent a month is a little over 60% a year, not 48%, because each month grows on the previous month's larger base. That gap is exactly what turns a comfortable-looking budget into an overrun in the final quarter.