How do I find the total size of my AWS S3 storage bucket or folder?

Does Amazon provide an easy way to see how much storage my S3 bucket or folder is using? This is so I can calculate my costs, etc.

Two ways,

Using aws cli

aws s3 ls --summarize --human-readable --recursive s3://bucket/folder/*

If we omit / in the end, it will get all the folders starting with your folder name and give a total size of all.

aws s3 ls --summarize --human-readable --recursive s3://bucket/folder

Using boto3 api

import boto3

def get_folder_size(bucket, prefix):
    total_size = 0
    for obj in boto3.resource('s3').Bucket(bucket).objects.filter(Prefix=prefix):
        total_size += obj.size
    return total_size

Amazon has changed the Web interface so now you have the "Get Size" under the "More" menu.

Answer updated for 2021 :)

In your AWS console, under S3 buckets, find bucket, or folder inside it, and click Calculate total size.

As of the 28th July 2015 you can get this information via CloudWatch.

aws cloudwatch get-metric-statistics --namespace AWS/S3 --start-time 2015-07-15T10:00:00 
--end-time 2015-07-31T01:00:00 --period 86400 --statistics Average --region us-east-1 
--metric-name BucketSizeBytes --dimensions Name=BucketName,Value=myBucketNameGoesHere 
Name=StorageType,Value=StandardStorage


Important: You must specify both StorageType and BucketName in the dimensions argument otherwise you will get no results.

Answer adjusted to 2020: Go into your bucket, select all folders, files and click on "Actions"->"Get Total Size"