Azure Backup Calculator

vault data per instance = first full backup + size × daily change rate × retained days, where retained days = daily points + weekly points × 7 + monthly points × 30; instance fee = $5 up to 50 GB, otherwise one block fee per 500 GB. Azure Backup bills a protected-instance fee that steps with the source size plus the vault storage the retention policy accumulates. After the first full copy every recovery point is an incremental, so vault growth is driven by the daily change rate multiplied by how long you keep history — long monthly retention dominates the total even though it stores few points.

Retention policies are usually copied from a template and never costed, yet extending monthly retention from 12 to 60 months multiplies vault storage several times over; this model ignores vault-side compression, so treat it as an upper bound and confirm current instance fees and storage rates in the Azure pricing calculator.

This calculator takes 9 inputs: Protected instances, Average protected size, Daily change rate, Daily recovery points kept, Weekly recovery points kept, Monthly recovery points kept, Instance fee up to 50 GB, Instance fee per 500 GB block, Vault storage price per GB. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.