Work out the destination capacity a laptop backup needs once incremental snapshots and retention are included.
Backup destination sizing is driven by retention, not by the size of the laptop. One full copy plus thirty days of incrementals at 3% daily change is roughly double the source data once compression is applied — and doubling the retention window doubles the incremental portion again. Compression and deduplication reduce both components by the same factor, typically 20-40% for a mixed document and media set, and the recommended disk adds 25% so the target does not fill mid-window.
Laptop Backup Storage
Total = full x fulls retained + data x daily change x retention days, all x (1 - compression)
Disk sizing
Recommended disk = total x 1.25 / 1024 to convert to TB with headroom
It sizes the retained full backups and the chain of daily incrementals separately, applies the compression and deduplication saving to both, and then adds 25% headroom before converting to a disk size.
Backups fail most often because the destination filled, and the cause is almost always retention rather than the source size. Sizing the incremental chain up front is what makes a thirty-day restore window actually available.
1-3% for a document-led workload, 5-10% for video editing, code builds or large database files. Virtual machine images and disk-image files change disproportionately because a small edit rewrites a large block.