CloudFront vs S3 Direct Calculator

It depends on your average object size, and that is the answer almost nobody gives. CloudFront is cheaper per byte, $0.085 per GB against S3's $0.09, with transfer from an S3 origin into CloudFront free rather than merely discounted. But it is more expensive per request: $1.00 per million HTTPS requests against S3's $0.40 per million GETs. At first-tier rates and before any free tier, the crossover sits around a 210 KB average object with nothing cached, falling to about 126 KB when everything is; the free tiers and volume discounts move it, and this calculator works it out at your volume. Above it, CloudFront wins outright. Below it, a CDN in front of an API serving small JSON responses can genuinely cost more.

Roughly 125 to 210 KB at first-tier US rates, before the free tier; the free tier lowers it, often a lot, and this calculator works it out for your traffic. CloudFront saves about half a cent per GB and costs about $0.60 extra per million requests once caching is accounted for, so the two cancel at somewhere between 5,000 and 8,300 requests per gigabyte depending on your hit rate. Video, images, installers and large downloads are comfortably above that line; API responses and small assets are below it.

In the US and Canada, data transfer out is tiered from $0.085 per GB down to $0.02 above 5 PB, plus $0.01 per 10,000 HTTPS requests. The AWS free tier covers 1 TB of transfer and 10 million requests a month. CloudFront also sells flat-rate plans per distribution, $15, $200 and $1,000 a month with usage allowances and no overage charges, which can cost less for steady traffic.

CloudFront does not charge for data transfer from an AWS origin. Your origin still charges its own request fee, every cache miss is an S3 GET at the normal rate, which is why a very low hit rate still costs something even though the transfer is free.

Considerably. CloudFront prices by the edge region serving the request, and South America, Asia Pacific and the Middle East cost materially more than the US and Europe. This calculator models US and Canada rates, so a globally distributed audience will pay more than shown unless the distribution is restricted to cheaper price classes.

It depends on object size more than on the hit rate. For large objects, none: the free origin transfer and the cheaper egress rate mean CloudFront wins even with nothing cached. For small objects, no hit rate is enough, because every request pays CloudFront's per-request fee whether it is cached or not. Only in between does a break-even hit rate exist. This calculator tells you which of the three cases your numbers fall in.