Database Growth Calculator
How large a database will grow given how many rows arrive each day and how big each one is — with indexes, overhead and the date it outgrows the disk.
Raw data is rows per day × bytes per row.
How the database growth calculator works
Raw data is rows per day × bytes per row. Real databases store considerably more than that: indexes commonly add 20–50% on top, and page overhead, alignment and free space add more again. The multiplier here covers both. Growth is linear if the arrival rate is steady, which is the assumption; a growth rate above zero compounds it monthly instead.
Formula: size after n days = rows/day × bytes/row × overhead × n (compounded if growing)
Worked examples
| Inputs | Data added over the period | Note |
|---|---|---|
| 100k rows/day of 500 bytes for a year | 25.55 GB | about 25.5 GB |
| A busy events table — 5M rows/day | 135 GB | about 135 GB in 90 days |
| Growing 10% a month | 36.8 GB | compounding makes the second half far larger |
FAQFrequently asked questions
How big is a typical row?
A few hundred bytes for ordinary business data; far more if rows contain long text or JSON. Check your own table rather than guessing.
Why add 40% overhead?
Indexes are stored separately and commonly add 20–50%; page headers, alignment and free space add more. Databases with many indexes can exceed the data itself.
Does deleting rows free space?
Not always immediately — most engines mark space reusable rather than returning it to the operating system until the table is rebuilt or vacuumed.
Should I plan for the average or the peak?
The peak. Storage that fills at 3am on the busiest day of the year still causes an outage.
What about backups?
Budget separately: several full backups plus transaction logs commonly need two to three times the live database size.
Where these figures come from
- IEC 80000-13 — Information science and technology (quantities and units) — the decimal (kB, MB) versus binary (KiB, MiB) prefixes used throughout
- RFC 4632 — Classless Inter-domain Routing (CIDR) — the address-plan arithmetic behind the subnet calculator
- RFC 1918 — Address Allocation for Private Internets — the private ranges the subnet calculator recognises
- NIST SP 800-63B — Digital Identity Guidelines, Authentication — length over composition rules; the basis of the password guidance here
- NIST SP 800-57 Part 1 — Recommendation for Key Management — key-strength comparisons used by the key-space calculator
- Australian Cyber Security Centre — Essential Eight — national guidance on passphrases and system hardening
Last checked: September 2026. Units follow the SI decimal convention (IEC 80000-13 defines the binary alternatives); network and security figures cite the defining standard.