Backup Storage Estimator
Calculate how much backup storage you need based on data size and retention policy.
Results
Choosing between full, incremental and differential backup strategies dramatically affects how much storage you need. Full backups are simple but expensive. Incremental backups save only daily changes and use the least space. Differential backups grow each day but are faster to restore than incrementals. This calculator estimates total storage requirements for any retention period.
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Frequently asked questions
For 500 GB of data with 4 weeks retention, you need 4 x 500 GB = 2 TB of backup storage. Each weekly backup is a complete copy, so storage requirements scale linearly with retention.
With 500 GB data, 5% daily change and 4 weeks retention: full backups need 2,000 GB while incremental needs only 1,200 GB (1 full + 28 daily 25 GB increments). That is a 40% storage saving.
Most businesses see 2-10% daily change. Office environments with documents typically change 3-5%. Databases and active development environments may change 10-20% daily.
Incremental backs up only what changed since the last backup (any type). Differential backs up everything that changed since the last full backup. Differentials grow each day but restore faster since you only need the last full plus the latest differential.
A common policy is 4 weekly full backups plus daily incrementals. For compliance, keep monthly archives for 1-7 years. The 3-2-1 rule recommends 3 copies, on 2 different media, with 1 offsite.