Capacity Exhaustion Calculator
Find when a resource runs out from its current usage and growth rate, including the date the upgrade trigger fires.
Inputs
Months Until Capacity Is Exhausted
10.9
Months Until the Upgrade Trigger
5.8
Current Utilisation
62.0%
Order the Upgrade Within
7.9months
Assessment
Runway of 10.9 months, order within 7.9 months
Step by step
Values used
Total capacity = 10,000 units; Currently used = 6,200 units; Growth per month = 4.50 %; Upgrade trigger threshold = 80 %; Upgrade lead time = 3 months
Capacity Exhaustion
months to exhaustion = ln(capacity ÷ used) ÷ ln(1 + monthly growth); order-by = exhaustion − lead time.
Months Until Capacity Is Exhausted
= 10.9
Months Until the Upgrade Trigger
= 5.8
Current Utilisation
= 62.0
Order the Upgrade Within
= 7.9 months
Assessment
= Runway of 10.9 months, order within 7.9 months
How it works
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.
Formula
Capacity Exhaustion
months to exhaustion = ln(capacity ÷ used) ÷ ln(1 + monthly growth); order-by = exhaustion − lead time.
- monthly growth
- Compound growth of consumption per month
- lead time
- Procurement plus installation time for the upgrade
Frequently Asked Questions
How is Capacity Exhaustion calculated?
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.
Why does Capacity Exhaustion matter?
The order-by date, not the exhaustion date, is the deadline the team actually has to hit, and it is routinely discovered too late.
What values do I need to enter?
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.
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