AWS S3: how do I see how much disk space is using

Yippe - an update to AWS CLI allows you to recursively ls through buckets...

aws s3 ls s3://<bucketname> --recursive  | grep -v -E "(Bucket: |Prefix: |LastWriteTime|^$|--)" | awk 'BEGIN {total=0}{total+=$3}END{print total/1024/1024" MB"}'

The command line tool gives a nice summary by running:

aws s3 ls s3://mybucket --recursive --human-readable --summarize