How to use this calculator
- Enter or choose current size.
- Enter or choose growth type.
- Enter or choose growth.
- Enter or choose months ahead.
- Enter or choose capacity limit.
- The projected size updates as you type. Use Copy result or Share to keep it.
Method
Linear: Size(m) = Size₀ + G × m; Compound: Size(m) = Size₀ × (1 + g)^m; Months to limit = (Limit − Size₀) ÷ G or ln(Limit ÷ Size₀) ÷ ln(1 + g)
- Size₀
- current size
- G
- GB added per month
- g
- monthly growth rate as a decimal
- m
- months ahead
Worked example
- Size in 12 months: 200 + 25 × 12 = 500 GB.
- Room left: 1,000 − 200 = 800 GB.
- Months to fill: 800 ÷ 25 = 32 months.
Growing 25 GB a month from 200 GB, the database reaches 500 GB in a year and a 1,000 GB limit in 32 months.
What the result means
Plan to act well before the limit: many databases slow down or need maintenance headroom before a disk is full, so treat 70–80% of capacity as the practical ceiling.
Assumptions and limits
- Growth continues at the entered rate for the whole period.
- Indexes, write-ahead logs, replicas, backups and fragmentation can make disk use larger than the data size. Measure the total on disk if you can.
Questions
Should I use linear or percentage growth?
Use GB per month when you add a steady amount of data (logs, orders). Use a percentage when growth tracks a user base that is itself growing.
Why are there two sizes?
Disk vendors use decimal GB (10⁹ bytes); many operating systems and databases report binary GiB (2³⁰ bytes), which is about 7% larger per unit.