Backup retention calculator
Turn daily, weekly, monthly and yearly retention rules into a calendar of backups to keep.
What the calculator shows
Enter the first and last backup dates, choose a daily or seven-day backup interval, and specify how many daily, weekly, monthly and yearly periods to retain. The planner highlights every simulated backup selected by at least one rule and lists the rules that selected it.
Overlapping rules do not create duplicate backups. A month-end backup can satisfy a daily, weekly and monthly rule at the same time and is counted once in the final retained set.
Example retention policy
| Rule | Periods | Meaning |
|---|---|---|
| Daily | 7 | Keep the latest backup from each of the seven most recent occupied days. |
| Weekly | 4 | Keep the latest backup from each of the four most recent occupied ISO weeks. |
| Monthly | 2 | Keep the latest backup from each of the two most recent occupied months. |
| Yearly | 0 | Do not add a yearly selection. |
For daily backups during August 2026, this example retains nine distinct backups: 16, 23 and 25–31 August. The weekly and monthly selections overlap with several of the daily selections.
How periods are interpreted
Daily periods use UTC calendar dates. Weekly periods use ISO weeks from Monday to Sunday. Monthly and yearly periods use UTC month and year boundaries. Empty periods are skipped, so a count of four weekly periods means the four most recent weeks that actually contain a simulated backup.
When this planner is useful
- Explaining a proposed retention policy before implementing it.
- Checking where daily, weekly and monthly rules overlap.
- Comparing policy changes without touching a backup repository.
- Preparing a discussion about capacity, compliance or recovery coverage.
Limits of the model
This is a generic policy simulator for one backup group. It does not execute deletions or reproduce every product's pruning behavior. It does not model full and incremental chain dependencies, legal holds, immutability, storage capacity or vendor-specific rules. Confirm a final policy in the documentation for your backup product and test it against real recovery requirements.
Does RetentionLab access my backups?
No. The planner generates sample dates from the values you enter and calculates the result in your browser. It does not connect to storage, upload backup metadata or delete snapshots.
For exact formulas, UTC boundaries and the reproducible worked example, read the retention methodology.