HNORIGIN · TOOLS

Backup Storage Sizing Calculator

Realistic backup capacity for deduplicating and plain disk targets. Modelled on how deduplication actually stores repeated full backups, instead of counting every full at full size.

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01Backup target

Where the backups are stored decides how repeated full backups are counted.

Deduplicating targetSoftware or appliance deduplication, for example Commvault, Cohesity, Rubrik or Data Domain.Plain disk or object storageNo deduplication, compression only. Every retained full is stored in full.

02Data to protect

Front-end size is the data being backed up, not the disk capacity. Example values are filled in: replace them with your own.

Daily change rate

Low Typical High Custom

WorkloadSize (TB)Daily changeDedup + compression (x:1)VMs and servers

Databases

File shares

Tip: your backup software's job history shows the real daily change (data written by incremental jobs ÷ front-end size). Enter it as Custom for a much tighter estimate than any profile.

03Retention

How many restore points you keep in each tier.

Daily

Weekly

Monthly

Yearly

04Planning

Size for where the data will be, not where it is today.

Growth per year

Plan for (years)

Free headroom

Copies

Advanced assumptions

How much unique data one retained point adds, as a multiple of one day's change. Blocks are overwritten, so a week of change is less than 7 days' worth. Used for deduplicating targets only.

Weekly (low / high)

Monthly (low / high)

Yearly (low / high)

Changed-block compression cap

Capacity to provision ↓–

CAPACITY TO PROVISION

–

Stored data today–

Stored data–

Restore points kept–

Logical data protected–

Overall reduction–

Where the space goes

Tier	Points kept	Stored

By workload

Workload	Data	Stored

Sizing a new backup target or renewal? HNOrigin can review your real job statistics and retention policies and give you a capacity plan you can defend.

Request a sizing review →

How the estimate works

First full backup: front-end data divided by your reduction ratio.
Daily restore points: each keeps that day's changed data. Changed blocks deduplicate far less than a full backup, so on a deduplicating target they are reduced by compression only, capped at 2:1 by default.
Weekly, monthly and yearly points on a deduplicating target add only the unique data that changed since the previous point in that tier, not a full copy. By default a week adds 2 to 4 days' worth of change, a month 4 to 8, and a year 12 to 24, never more than the whole data set. These multipliers are editable under Advanced assumptions.
Overlapping tiers: points that fall inside a shorter tier's window (for example 4 weekly points inside 30 daily points) add no extra data.
Plain disk or object storage: assumes a weekly full with daily incrementals, and every retained full is stored in full after compression.
Growth compounds yearly over your planning period. Headroom is added on top, because a backup target should never run full: garbage collection, retention overlap and re-run jobs all need free space.
The range comes from the change-rate profile and the unique-change multipliers. The reduction ratio is used exactly as entered: lower it to be more conservative.

Planning estimate only. Real results depend on data type, backup software, configuration and how your data actually changes. Validate against your backup software's job statistics and your vendor's sizing tools before buying storage.