Find when a resource runs out from its current usage and growth rate, including the date the upgrade trigger fires.
Consumption compounds, so linear extrapolation over-estimates the runway. Inverting the compound-growth formula gives both the exhaustion point and the earlier upgrade-trigger crossing, and subtracting the lead time gives the date by which the purchase order must be raised. The order-by date, not the exhaustion date, is the deadline the team actually has to hit, and it is routinely discovered too late.
Capacity Exhaustion
months to exhaustion = ln(capacity ÷ used) ÷ ln(1 + monthly growth); order-by = exhaustion − lead time.
months to exhaustion = ln(capacity ÷ used) ÷ ln(1 + monthly growth); order-by = exhaustion − lead time. Consumption compounds, so linear extrapolation over-estimates the runway. Inverting the compound-growth formula gives both the exhaustion point and the earlier upgrade-trigger crossing, and subtracting the lead time gives the date by which the purchase order must be raised.
The order-by date, not the exhaustion date, is the deadline the team actually has to hit, and it is routinely discovered too late.
This calculator takes 5 inputs: Total capacity, Currently used, Growth per month, Upgrade trigger threshold, Upgrade lead time. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.