S3 CRR vs SRR cost: what changes (transfer, storage, requests)

If you're choosing between cross-region replication (CRR) and same-region replication (SRR), the cost difference usually comes down to one thing: whether replicated bytes are billed like cross-region transfer. This checklist helps you compare the real line items.

Start with the same 3 buckets

  • Replicated data (GB/month): the changed data copied from source to destination.
  • Replica storage: you store (almost) the same objects twice.
  • Extra requests: replication can increase PUT/GET/LIST/HEAD activity.

What changes between CRR and SRR

  • CRR: often includes cross-region transfer-like charges (or a per-GB replication fee, or both).
  • SRR: avoids cross-region transfer, but still duplicates storage and may add request costs.

Step 1: estimate replicated GB/month (changed data)

The biggest modeling mistake is using total bucket size. Replication volume is driven by writes and churn. Use this guide: estimate replication GB/month.

Step 2: price the per-GB replication line item

Use a per-GB assumption based on your plan:

Step 3: add replica storage

Treat replica storage as a separate ongoing line item (GB-month). Use Object storage cost calculator and add the replica stored GB as another storage line item.

Step 4: sanity-check request fees

For millions of small objects, request fees can matter. Use S3 request cost calculator or model requests in the Object storage cost calculator.

Validation checklist (before you choose CRR vs SRR)

  • Validate your goal: DR/multi-region reads (CRR) vs durability inside a region (SRR).
  • Validate replicated GB/month from write volume and churn (do not use bucket size).
  • Validate destination storage class and lifecycle policies (replica defaults matter).
  • Validate whether replication is billed as a feature fee, transfer, or both in your provider/region.

Worked comparison template (copy/paste)

  • Replicated GB/month = changed data per month (baseline + peak)
  • CRR per-GB fee = replication/transfer line item (if applicable)
  • SRR per-GB fee = replication line item (usually lower transfer component)
  • Replica storage = destination GB-month (by storage class)
  • Requests = extra PUT/GET/LIST/HEAD per month (many small objects scenario)

Common pitfalls

  • Comparing CRR vs SRR based on total bucket size instead of changed data per month.
  • Forgetting destination storage class (replica defaults to hot tier unless configured).
  • Ignoring peak replication windows (deployments/backfills can spike changed data).

Related guides

S3 replication cost Copy storage pricing S3 pricing explained

Sources

Related guides

S3 pricing explained: storage vs requests vs egress
A practical breakdown of S3-like object storage pricing: GB-month storage, request fees, and data egress - plus how to estimate each without missing hidden line items.
Storage Costs Explained (GB-month, requests, retrieval)
A practical storage cost model: GB-month, requests, retrieval, and transfer. Includes estimation checklist.
Copy storage pricing: what you pay for when data moves
A practical guide to pricing storage copy operations (cross-region copy, replication, backups) across S3-like object storage: transfer, requests, and extra storage.
S3 to Glacier transfer cost: what to include in the move
A practical checklist for S3 to Glacier transfer cost: transition requests, minimum storage duration, and any transfer or rewrite overhead.
S3 replication cost: how to estimate cross-region replication
A practical guide to estimating S3 replication cost: what data volume to count, which fees to expect, and how to model replica storage, requests, and transfer. Includes a fast checklist.
S3 pricing: a practical model for storage, requests, egress, and replication
A practical S3 pricing guide: what to include (GB-month, requests, egress, replication) and how to estimate the key inputs without copying price tables.

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.
RPS to Monthly Requests Calculator
Estimate monthly request volume from RPS, hours/day, and utilization.
API Request Cost Calculator
Estimate request-based charges from monthly requests and $ per million.

FAQ

Is CRR always more expensive than SRR?
Usually yes because CRR often adds cross-region transfer-like charges, but the real driver is replicated GB/month (changed data). Storage and request fees can dominate depending on workload.
What is the main input for replication cost models?
Replicated GB/month (changed data), not total stored GB. Estimate it from write volume and churn, then price the per-GB replication/transfer line item.
Do I need to include destination storage?
Yes. Replication typically means storing a second copy of data. Destination storage is often the largest ongoing cost.
Last updated: 2026-01-27