Storage Growth
Project future storage capacity needs based on current usage and growth rate.
About Storage Growth
Capacity planning at its simplest divides the remaining free space by the rate at which it's being consumed — this gives a linear projection of when storage will run out if current growth trends continue unchanged. It's a first-pass planning tool rather than a precise forecast, since real growth is rarely perfectly linear; seasonal spikes, data purges, and new application onboarding can all shift the actual runway significantly from this estimate.
Formula
Months to full
months_to_full = (total_capacity − used_capacity) / monthly_growth
Worked example
With the default values below, Storage Growth returns Months Until Full of 13.3. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Total Capacityminimum 0 TB
- 100 TB
- Currently Usedminimum 0 TB
- 60 TB
- Monthly Growthminimum 0.01 TB
- 3 TB
Results
- Months Until Full
- 13.3 months
- Remaining Capacity
- 40.00 TB
- Current Usage
- 60.0%
- Projected Full Date
- December 9, 2027
Step by step
- 1Values used
- 2Months to full
- 3Months Until Full= 13.3 months
- 4Remaining Capacity= 40.00 TB
- 5Current Usage= 60.0
- 6Projected Full Date= 2027-12-09
Assumptions and limits
- The result is derived only from the 3 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 2 decimal places, 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
Why is a linear growth model not always accurate?
Real storage growth is often non-linear — new projects or data sources can cause step-changes in growth rate, retention policy changes or archival/purge jobs can cause sudden drops, and growth itself frequently accelerates over time as an organization's data footprint expands. Use this as an early-warning estimate and revisit it monthly with updated actuals.
At what usage percentage should I start planning for expansion?
Most storage teams start capacity expansion planning at 70-80% utilization, since procurement, provisioning, and migration lead times (especially for SAN/NAS hardware) can take weeks to months — waiting until near 100% risks an outage before new capacity arrives.
How should I handle irregular or seasonal growth patterns?
Use an average monthly growth rate calculated over several recent months (not just the last month) to smooth out one-off spikes, and re-run this calculation regularly rather than treating a single projection as fixed — trending the projected full date over time reveals whether growth is accelerating or stabilizing.