Estimating and understanding what AWS EC2 EBS Snapshots will cost you can be more difficult than you may think.

Here are some key points to keep in mind:

• Snapshots are not compressed. Therefore your first snapshot will be equal to the GiB used in the source EBS volume.
• Additional snapshots are incremental. Each incremental snapshot uses pointers, pointing to the prior snapshot’s blocks that have not changed. New blocks are recorded.
• You can use the AWS Cost Explorer to view past usage. Today is not available. Filter down by “Usage Type Group” and set the value to “EC2: EBS – Snapshots”. Narrow down further by region and/or tag.
  • Usage (GB) are measured by “GB-Month”. So if there are 30 days in that month, multiple the metric by 30 to get that day’s actual usage.
• As of 12/10/2018, the cost of a snapshot is $0.05/GB/mo

The hard part is estimating the amount of change per snapshot. The most lenient method would be to use a 100% change value. But that’s not practical.

Let’s say you estimate that 3% of your total volume size will be modified per snapshot. Therefore plan on an additional cost of $.15/mo for every 100 GiB of used volume space on every snapshot produced..