Project the rest of the year from spend to date, month-on-month growth and a new workload, then test it against the budget.
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.
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 = 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.
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.
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.
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.