Estimate full and incremental backup sizes based on data volume and change rate.
A full backup captures everything; incremental backups capture only what changed since the previous backup (full or incremental), so their combined size grows linearly with the daily change rate. Differential backups instead capture everything changed since the last full backup, so each successive differential grows larger as the cycle progresses, trading more storage for simpler, faster restores (only the last full + last differential are needed, versus a full + every incremental in sequence).
Total storage with incrementals
total = full + (daily_change% × full × num_incrementals)
Total storage with differentials
total = full + Σ(daily_change% × full × day) for day = 1 to num_incrementals
Incremental backups capture only the changes since the most recent backup of any type (full or incremental), keeping each backup small. Differential backups capture all changes since the last full backup, so each one grows larger over the cycle but restoration only needs the full plus the single latest differential.
Incremental backups almost always use less total storage than differential backups over the same cycle, because differentials repeatedly re-capture changes that earlier differentials in the same cycle already recorded.
Differential backups restore faster because you only need the last full backup plus the single most recent differential. Incremental restores require replaying the full backup plus every incremental in sequence since it, which takes longer and has more failure points.