Capacity Exhaustion Calculator

Find when a resource runs out from its current usage and growth rate, including the date the upgrade trigger fires.

About Capacity Exhaustion Calculator

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

Worked example

With the default values below, Capacity Exhaustion Calculator returns Months Until Capacity Is Exhausted of 10.9. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total capacityaccepts 1–1,000,000,000 units: 10,000 units
Currently usedaccepts 0–1,000,000,000 units: 6,200 units
Growth per monthaccepts 0–200 %: 4.5 %
Upgrade trigger thresholdaccepts 10–100 %: 80 %
Upgrade lead timeaccepts 0–60 months: 3 months

Results

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

Step by step

1Values used
2Capacity Exhaustion
3Months Until Capacity Is Exhausted= 10.9
4Months Until the Upgrade Trigger= 5.8
5Current Utilisation= 62.0
6Order the Upgrade Within= 7.9 months
7Assessment= Runway of 10.9 months, order within 7.9 months

Assumptions and limits

The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, 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 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.