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Backup storage calculator: retention and restore time
The short answer: you need one full copy, plus the changes you keep, plus any weekly, monthly and yearly copies, for every location you store backups in. Enter your data size and retention to see the total, and how long a full restore would take.
Your data
Retention
Copies and restore
Weekly, monthly and yearly copies are counted as full copies. Forever-incremental and synthetic-full schemes use less; your backup software's own sizing tool will refine the figure.
Storage you need
0 TB in total
0 TB per copy
Full restore, best case
0 hours
Data size ÷ bandwidth. Real restores take longer.
Next steps
Size it, then prove it restores.
- Keep at least one copy offline or immutable, so ransomware cannot encrypt it.
- Test a restore on a schedule. Why untested backups fail.
- Compare where to keep copies: NAS vs cloud backup.
- Set recovery targets in a disaster recovery plan, then check your score with the cyber-readiness score.
Services: backup, disaster recovery and cloud and FortGrid backup and DR.
Common questions
About backup sizing.
How much backup storage do I need?
Roughly one full copy of your data, plus the daily changes you keep, plus any weekly, monthly and yearly full copies your retention policy requires, divided by whatever saving compression and deduplication give you. Then multiply by the number of copies you keep in different places. The calculator does that sum for you.
What is the 3-2-1 backup rule?
Keep three copies of your data, on two different types of storage, with one copy off-site. Many organisations now add an offline or immutable copy so ransomware cannot encrypt the backups as well.
How long would a full restore take?
At best, the data size divided by the usable bandwidth between the backup and the systems you are restoring. Real restores are slower because of disk speed, verification and the order you bring systems back. Use the figure as a lower limit when you set a recovery time objective.
What compression or deduplication ratio should I use?
Use the figure your backup software reports for your own data. It varies widely: databases and documents compress well, while photos, video and encrypted files barely compress. If you do not know, leave it at 1 for a worst case.
Is anything I enter sent to Missan?
No. The calculation runs in your browser. Nothing is sent unless you use the optional form and press send.
Email me my results, or get a backup review
Your figures are attached automatically. We reply within one business day.
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