Why is AWS S3 egress bandwidth so expensive compared to Cloudflare R2?

AWS charges up to $0.09 per gigabyte for data transfer out (egress) beyond the first 100 GB/month. This 'egress tax' is a deliberate customer lock-in mechanism. In contrast, Cloudflare leverages its existing global edge network (anycast CDN) and charges exactly $0.00 in egress bandwidth fees on Cloudflare R2, meaning you only pay for stored data ($0.015/GB-mo) and API operations.

What is the difference between Class A and Class B API operations?

Class A operations modify or query object metadata, including PUT, POST, LIST, and COPY requests (e.g., uploading files or listing bucket contents). These are billed at higher rates (typically $4.50 to $5.00 per million requests). Class B operations are read-only retrieval requests (GET, HEAD) and are substantially cheaper (typically $0.36 to $0.40 per million requests).

Can I use Cloudflare R2 or Backblaze B2 as a drop-in replacement for AWS S3?

Yes. Both Cloudflare R2 and Backblaze B2 offer full S3 API compatibility. You can use existing AWS SDKs (Boto3 in Python, AWS SDK for JavaScript/TypeScript, Go, or PHP), Terraform, and tools like rclone simply by updating the S3 endpoint URL and entering your API access and secret keys.

How does Backblaze B2 free egress work with Cloudflare?

Through the Bandwidth Alliance partnership, Backblaze waives 100% of egress fees when data is routed through Cloudflare's CDN. Additionally, standard standalone Backblaze B2 accounts provide free egress up to three times your total monthly stored data volume, charging just $0.01/GB for any bandwidth beyond that limit.

Cloud Storage & Egress Cost Calculator 2025/2026 — AWS S3 vs Cloudflare R2 vs Backblaze B2

Cloud Economics & Systems Architecture (2025/2026)

The True Cost of Cloud Object Storage: Demystifying AWS Egress Bandwidth & S3-Compatible Alternatives

In cloud computing architecture, storage pricing is deceptively divided into three separate billing vectors: data at rest (GB-months), API request operations (Class A and B), and outbound data transfer (egress). While base storage costs across providers differ by modest margins, the disparity in outbound data transfer fees is astronomical.

Amazon Web Services (AWS S3) charges up to $0.09 per gigabyte of outbound traffic. For video streaming services, SaaS applications distributing software packages, or web apps serving rich media, bandwidth charges routinely exceed raw storage costs by 500% to 1,000%. Modern S3-compatible alternatives such as Cloudflare R2 and Backblaze B2 have disrupted this pricing model by eliminating or drastically subsidizing egress network fees.

Object Storage Billing Equations US-East Region Standard Rates

// 1. Total Monthly Cloud Storage Cost Formula

Total_Bill = Cost_Storage + Cost_Egress + Cost_ClassA_Ops + Cost_ClassB_Ops

// 2. AWS S3 Tiered Egress Equation

Egress_S3 = max(0, Egress_GB - 100) × $0.090 [Up to 10 TB]

Egress_S3 = (9,900 × $0.090) + (Egress_GB - 10,000) × $0.085 [Next 40 TB]

// 3. Cloudflare R2 Formula (Zero Egress)

Cost_R2 = max(0, Storage_GB - 10) × $0.015 + $0.00 (Egress) + Ops_Fee

// 4. Backblaze B2 Formula (3x Free Egress)

Cost_B2 = max(0, Storage_GB - 10) × $0.006 + max(0, Egress_GB - (3 × Storage_GB)) × $0.010

Underwriting Variables & Rate Definitions:

AWS S3 Standard: $0.023/GB-mo for first 50 TB. Egress: $0.09/GB. Class A: $0.005/1,000. Class B: $0.0004/1,000.
Cloudflare R2: $0.015/GB-mo. $0.00 Egress. 1M Class A free then $4.50/M. 10M Class B free then $0.36/M.
Backblaze B2: $0.006/GB-mo. Free egress up to 3x monthly stored volume, then $0.01/GB. Free through Cloudflare CDN.
Google Cloud Storage (Standard): $0.020/GB-mo. Egress: $0.12/GB (first 1 TB), then $0.11/GB.
DigitalOcean Spaces: $5.00/mo flat fee including 250 GB storage and 1,000 GB egress. Excess storage at $0.02/GB; excess egress at $0.01/GB. Unlimited free API requests.

Frequently Asked Questions

Why is AWS S3 egress so expensive compared to Cloudflare R2? ▼

AWS charges up to $0.09 per GB to exit their network, generating multi-billion-dollar profit margins that disincentivize customers from migrating data. Cloudflare monetizes edge network transit at scale and chose to disrupt the market by offering R2 with guaranteed zero egress fees.

Can I switch from AWS S3 without rewriting my codebase? ▼

Yes. Cloudflare R2, Backblaze B2, and DigitalOcean Spaces implement the S3 API specification. In your Python, Node.js, Go, or Ruby codebase, you simply change the endpoint URL and input your access keys. Existing SDKs (Boto3, AWS SDK) work seamlessly.

When is Backblaze B2 better than Cloudflare R2? ▼

Backblaze B2 is superior for large-scale data backup, disaster recovery, and cold archives where data volume is high (e.g. 50+ TB) but monthly downloads are modest. At $0.006/GB, Backblaze storage is 60% cheaper than Cloudflare R2 ($0.015/GB). For high-egress web and streaming apps, Cloudflare R2 wins.

Cloud Storage & Egress Bandwidth Cost Calculator (2025/2026)

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Slash Your S3 Storage Bill with DigitalOcean Spaces or Cloudflare R2

The True Cost of Cloud Object Storage: Demystifying AWS Egress Bandwidth & S3-Compatible Alternatives

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