S3 replication pricing: estimate replicated GB/month and total impact

The biggest input in S3 replication pricing is replicated GB/month. That volume is driven by writes and churn, not by total stored data.

Replication inputs

  • Replicated GB: data copied per month.
  • Request costs: replication requests and PUTs.
  • Destination storage: GB-month in target bucket.

What to model (replication is not one number)

  • Replicated GB/month: changed data replicated (steady-state driver)
  • One-time backfill: initial copy of existing objects (migration/enablement event)
  • Destination storage: replica storage GB-month (often the largest ongoing cost)
  • Request overhead: extra PUT/COPY/LIST and control-plane activity can show up for high-churn buckets
  • Region boundary: CRR can introduce transfer-like costs compared to SRR

1) Estimate replication volume from writes (steady-state)

Use this guide to estimate replicated GB/month from GB/day writes or PUT counts and object size.

Replication volume tracks changed bytes. If your workload rewrites objects often (churn), replicated GB/month can be much larger than "new data added".

2) Price the per-GB replication line item (and keep backfill separate)

Use a per-GB assumption that matches your plan (feature fee, transfer-like pricing, or both):

  • Create a backfill scenario for the initial copy (bucket size at enablement time).
  • Create a steady-state scenario for replicated GB/month from writes/churn.

3) Don't forget destination storage

Replication typically means storing the data twice. Add destination storage as a separate line item using object storage cost.

4) CRR vs SRR: when the option changes cost

If you're deciding between cross-region replication (CRR) and same-region replication (SRR), use this checklist: S3 CRR vs SRR cost.

Common pitfalls

  • Using total bucket size as the monthly replication input (unless you are modeling a one-time backfill).
  • Missing churn: frequent overwrites and deletes create replicated bytes that do not show up as "growth".
  • Forgetting destination storage GB-month (replication is usually double storage).
  • Not separating CRR transfer-like effects from SRR.
  • Assuming replication is "free" operationally: backlog and retries during incidents can create peaks.

How to validate the estimate

  • After enablement, reconcile replicated bytes and replica storage in CUR/Cost Explorer.
  • Validate replication volume by sampling writes/day and object sizes for a representative week.
  • Track one-time events separately (backfills, migrations, reprocessing).

Related tools

S3 replication cost calculator Copy storage pricing S3 replication cost

Related tools

S3 cost S3 requests Egress Storage costs

Sources

Related guides

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Related calculators

Data Egress Cost Calculator
Estimate monthly egress spend from GB transferred and $/GB pricing.
API Response Size Transfer Calculator
Estimate monthly transfer from request volume and average response size.
VPC Data Transfer Cost Calculator
Estimate data transfer spend from GB/month and $/GB assumptions.
Cross-region Transfer Cost Calculator
Estimate monthly cross-region transfer cost from GB transferred and $/GB pricing.

FAQ

What's the key input for S3 replication pricing?
Replicated GB/month based on changed data (writes and churn). Total bucket size is usually the wrong input unless you're doing a one-time backfill.
Do I need to include destination storage?
Yes. Replication typically means storing the data twice. Destination storage is often the biggest ongoing cost.
How do I compare CRR vs SRR costs?
CRR often adds cross-region transfer-like charges compared to SRR. Compare transfer/feature fees, replica storage, and request fees with a consistent checklist.
Last updated: 2026-02-07