How can I get the size of an Amazon S3 bucket?


s3cmd seems to access every file individually and isn't very scalable. Is there a scalable way to get the answer?

Edit: Ideally via the command line.

asked 3 years ago2074 views
4 Answers

In the CLI you can list recursively and summarize in a human readable format.

aws s3 ls s3://mybucket --recursive --human-readable --summarize
... [snipped output] ...
Total Objects: 46
   Total Size: 29.5 MiB
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answered 3 years ago
profile pictureAWS
reviewed 2 years ago
  • Will that work if your bucket has, say, 50 million objects in it?

  • It should work, though it will take a long time. I just listed a bucket with 6,363,094 objects, 24.9 GiB in size. Took 54 minutes.


Using the BucketSizeBytes CloudWatch Metric (ref: is probably your best bet - and being it CloudWatch, you can also alarm on size, use triggers etc as you would do with any other metric.

Need to be careful though, this metric might be a few hours behind.

answered 3 years ago
profile pictureAWS
reviewed 2 years ago

In the S3 console you can go navigate to your bucket and select all objects in the bucket. Once all objects are selected you can go to "Actions" > "Calculate total size" Hope that helps

answered 3 years ago
  • Is there a command line version of that?

  • Not that i am aware of. You could try this command though. Output is in bytes fyi:

    aws s3api list-objects --bucket BUCKETNAME --output json --query "[sum(Contents[].Size), length(Contents[])]"


There are alternative ways.

  • Cloudwatch Metrics.
  • Cost Explorer API, UI or Billing.
  • Generate an S3 Inventory, use Athena to run query to sum sizes. Might be overkill though, but you can filter as you wish if you need more than just the usage data.
answered 2 years ago

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