S3 replication cost explained: what CRR and SRR really bill

Quick answer

S3 replication has no per-feature fee, but it bills on four lines: a second copy of every object stored at the destination (for example another $0.023 per GB in S3 Standard), PUT requests at the destination ($0.005 per 1,000), inter-region data transfer for Cross-Region Replication (about $0.02 per GB), and, if enabled, Replication Time Control at $0.015 per GB plus replication metrics. Same-Region Replication skips the data-transfer line. The single biggest cost is usually the duplicate storage, so replicating everything into S3 Standard when a cheaper class or a filtered subset would do is the common mistake.

Turning on S3 replication is one click, which hides the fact that it can roughly double the storage cost of a bucket and add data-transfer charges on top. Replication itself has no line-item fee; you pay for the resources it consumes. Understanding those four resources is the difference between replication that costs a little and replication that quietly doubles a large bill.

The four cost lines

Line	What it charges	Rate (us-east-1)
Destination storage	A full second copy of each object	$0.023/GB Standard
PUT requests	One replication PUT per object	$0.005 per 1,000
Data transfer (CRR)	Bytes moved between regions	~$0.02/GB
Replication Time Control	Optional 15-minute SLA	$0.015/GB + metrics

Destination storage is almost always the largest of the four. Replicating a 50 TB bucket into S3 Standard in another region adds about $1,150 per month in storage alone, before a single byte is transferred. The PUT cost is modest unless you have huge object counts: replicating 100 million new objects a month costs about $500 in replication PUTs. Data transfer applies only to Cross-Region Replication (CRR); Same-Region Replication (SRR) moves data within a region and avoids the roughly $0.02 per GB transfer fee entirely.

CRR versus SRR on cost

CRR and SRR share the same storage and request pricing; the difference is the data-transfer line. CRR to another region adds about $0.02 per GB of replicated data, so replicating 50 TB across regions is roughly $1,000 in transfer the first time it copies, then only new and changed objects thereafter. SRR keeps both copies in one region for compliance, log aggregation, or account separation, and pays no transfer. If your driver is durability or latency rather than a genuine cross-region requirement, SRR is materially cheaper. The data transfer guide and the general cross-region replication article cover the transfer side in more depth.

Replication Time Control

Replication Time Control (RTC) guarantees that 99.99 percent of objects replicate within 15 minutes, backed by an SLA. It adds $0.015 per GB of replicated data plus CloudWatch replication metrics. On a bucket replicating 20 TB per month that is roughly $300 extra, purely for the timing guarantee. RTC is worth it for disaster-recovery workloads with a strict recovery point objective, and wasteful for casual backup where a few hours of replication lag is harmless. Enable it only where the SLA is actually required.

How to keep replication cheap

Three levers do most of the work. First, replicate a subset: use replication rules with prefix or tag filters so only the objects that need a second copy are replicated, not the entire bucket. Second, choose a cheaper destination class: replicating into Standard-IA ($0.0125 per GB) or Glacier Instant Retrieval ($0.004 per GB) for a backup copy can cut destination storage by half or more, since a DR copy is rarely read. Third, expire old replicated objects with a lifecycle policy at the destination so the copy does not grow forever. Compare classes in the storage class comparison before you pick the destination.

Price it before you enable it

Replication is easy to justify on durability and compliance grounds and easy to under-cost, because the duplicate storage lands quietly and the transfer shows up only after the first big copy. Estimate the four lines against your object count, growth rate, and destination class before turning it on, and price the configuration against the resource catalog so the second copy is a budgeted decision rather than a doubling you discover next month.

FAQ

How much does S3 replication cost?

There is no per-feature fee. You pay for a full second copy of every object at the destination (for example $0.023 per GB in S3 Standard), replication PUT requests at $0.005 per 1,000, inter-region data transfer of about $0.02 per GB for Cross-Region Replication, and optionally Replication Time Control at $0.015 per GB plus metrics. Destination storage is usually the largest line.

What is the difference in cost between CRR and SRR?

Cross-Region Replication (CRR) and Same-Region Replication (SRR) share the same storage and request pricing, but only CRR incurs inter-region data transfer at about $0.02 per GB. SRR keeps both copies in one region and pays no transfer, so if your goal is durability or account separation rather than a true cross-region requirement, SRR is cheaper.

Is Replication Time Control worth the cost?

RTC adds $0.015 per GB plus CloudWatch metrics to guarantee 99.99 percent of objects replicate within 15 minutes, backed by an SLA. It is worth it for disaster recovery with a strict recovery point objective, and wasteful for casual backup where a few hours of lag is harmless. Enable it only where the timing SLA is genuinely required.

How do I reduce S3 replication cost?

Replicate only a subset using prefix or tag filters instead of the whole bucket, choose a cheaper destination storage class like Standard-IA or Glacier Instant Retrieval for a rarely-read DR copy, and expire old replicated objects with a lifecycle policy at the destination. Together these can cut replication cost by half or more versus mirroring everything into Standard.

How does C3X help with S3 replication cost?

C3X prices S3 buckets and replication configuration from Terraform before deploy, so the destination storage class, filters, and whether RTC is enabled are visible in the pull request. That surfaces the duplicate-storage and transfer cost of replication at design time, letting teams choose a cheaper destination or a filtered subset before the second copy starts billing.

What to do next

See what replication really adds before you enable it. C3X prices S3 replication from Terraform against a live resource catalog. Start with the quickstart.