Storage is cheap; moving data out is not. On Amazon S3, a busy bucket's bill is often dominated by data transfer to the internet, while Cloudflare R2 charges nothing for egress. This calculator shows which one is cheaper for your storage and traffic.
How it works
S3 Standard in US East costs $0.023 per GB-month for storage. Data transfer out to the internet is free for the first 100 GB a month, then $0.09 per GB for the first 10 TB, falling in tiers to $0.05 per GB above 150 TB. Requests cost $5 per million writes and $0.40 per million reads.
R2 costs $0.015 per GB-month with the first 10 GB free, and egress is free. Requests cost $4.50 per million writes after 1 million free and $0.36 per million reads after 10 million free.
Prices were verified in September 2026 and change occasionally. Other S3 storage classes, regions, and CDN caching in front of either service will change the result.
A worked example
Storing 1,000 GB and serving 5,000 GB a month with 1 million writes and 10 million reads: S3 costs $23 for storage, $441 for data transfer and $9 for requests, $473 in total. R2 costs $14.85 for storage and nothing for the first 1 million writes and 10 million reads, so R2 saves $458.15 a month.
Questions people ask
Why is S3 egress so expensive compared with storage?
S3 prices storage and data transfer separately. Storing a file is a small, steady cost, but every time it is downloaded you pay again. For content that is read often, transfer quickly becomes the largest line on the bill.
When is S3 still the better choice?
When data is rarely read, when it is used mostly by other AWS services in the same region (which avoids internet egress), or when you need S3-specific features and storage classes.
Does a CDN change the math?
Yes. Serving files through a CDN reduces how often they are read from storage. With S3 behind CloudFront, transfer is billed by CloudFront instead, at its own rates.
Guides
- Why Your S3 Bill Is Mostly Egress, and When R2 Is CheaperStoring data on S3 is cheap. Serving it to the internet isn't. Here's how egress dominates a busy bucket's bill, with a worked S3 vs R2 comparison.
- Why Your 1 TB Drive Shows Only 931 GBNo storage is missing. Drive makers count in powers of 1,000 and most operating systems count in powers of 1,024, so the same bytes get two different labels.