Backup storage calculator
Estimate full copies plus retained daily changed data before planning backup capacity.
Enter your values or select local files.
A planning estimate, not a backup service. Assumes constant changed data, no compression or deduplication, and independent retained changes. Retention chains and full-backup schedules can change actual usage.
Formula
GB = (source GB × full copies + daily changed GB × retained days) × (1 + buffer % ÷ 100).
Worked example
100 GB × 2 + 2 GB × 30 = 260 GB; with 20% extra capacity = 312 GB.
How to use this tool
Enter values or select the relevant local data.
Review the result, example and assumptions.
Reset the tool or export a reviewable plan.
Good questions. Clear answers.
What does this tool calculate?
Estimate full copies plus retained daily changed data before planning backup capacity.
What assumptions and limits apply?
A planning estimate, not a backup service. Assumes constant changed data, no compression or deduplication, and independent retained changes. Retention chains and full-backup schedules can change actual usage.
What calculation does it use?
GB = (source GB × full copies + daily changed GB × retained days) × (1 + buffer % ÷ 100).