Storage Growth Calculator
Project how many months until storage capacity is exhausted given current usage and monthly growth rate.
Inputs
Months Until Full
13.3months
Remaining Capacity
40.00TB
Current Usage
60.0%
Projected Full Date
September 20, 2027
Step by step
Values used
Total Capacity = 100 TB; Currently Used = 60 TB; Monthly Growth = 3 TB
Months to full
months_to_full = (total_capacity − used_capacity) / monthly_growth
Months Until Full
= 13.3 months
Remaining Capacity
= 40.00 TB
Current Usage
= 60.0
Projected Full Date
= 2027-09-20
How it works
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
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.