I have two AWS accounts. In the first Account, I have data in S3. And I have an application running on Ec2 instance in 2nd Account. Both are in the same region

I have mounted the s3 of the first account to Ec2 instance in the second account.

I'm able to witness the data transfer in glances if I create or duplicate(copy existing file) any file on mounted s3 which is pretty obvious.

My question is will AWS charge for the data transfer from Ec2 to S3 which are in same region but different accounts.


In short: you will not be charged, so long as you use an S3 endpoint in your VPC.

The Data Transfer tab of S3 Pricing tells you what you need to know.

You pay for all bandwidth into and out of Amazon S3, except for the following:

 - Data transferred in from the internet.
 - Data transferred out to an Amazon Elastic Compute Cloud (Amazon EC2) instance, when the instance is in the same AWS Region as the S3 bucket.
 - Data transferred out to Amazon CloudFront (CloudFront).

There's a useful Open Guide on AWS Costs, which has a great graphic to describe costs.

One key thing to understand if you do cross account is each account may call a physical data centre a different name, so you need to use the AZ ID in that case.

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Data transfers are free if you are within the same region, within the same availability zone, and use a private IP address. Data transfers within the same region, but in different availability zones, have a cost associated with them.

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  • I have mounted the s3 to my EC2. – Siva Jun 30 at 15:53

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