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.
Inputs
Use the trailing three-month average, not the last single month.
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
12.2month 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
Values used
Spend so far this year = 700,000 USD; Months already billed = 4 months; Latest full month of spend = 190,000 USD/month; Month-on-month growth = 4 %; New workload landing later in the year = 25,000 USD/month; Month the new workload starts = 7 month of year; Savings actions already committed = 6 %; Annual budget = 2,600,000 USD/year
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).
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
How it works
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
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.