Cloud egress cost calculator: AWS, Google Cloud, Azure, Cloudflare and Fastly side by side

How it is calculated

V        = monthly_outbound_tb × tb_to_gb          (GB in a TB as each vendor defines it)
V_origin = V × (1 − cache hit ratio)               (with a CDN; otherwise V_origin = V)

C_tier(X) = Σ_i  r_i × min( max(X − F − B_(i−1), 0),  B_i − B_(i−1) )
F = free allowance, B_i = cumulative tier bounds measured after F, r_i = rate in tier i
r_i = Σ_g  w_g × r_(g,i)   (w = destination mix as shares of 1; g = North America and Europe, Asia Pacific, rest of the world)

C_total = C_tier(V_origin) + C_cdn(V) + V × p_az × r_az + V × p_reg × r_reg
r_az is doubled when the provider bills both directions
Origin pulls into the provider's own CDN are 0 when the dataset marks origin_to_cdn_free

effective $/GB = C_total ÷ V
difference vs current = C_total − C_total(current provider)

Assumptions

• Prices are list prices in USD from the dated table below. Negotiated discounts, commitments, request fees, plan or package fees and taxes are not modelled.
• Tiers are consumed by the total monthly volume. Where a vendor publishes a separate ladder per destination region, the three destination groups each use one representative rate card (named in the data notes) and the tier rate is the destination-mix-weighted average.
• One CDN is applied in front of every origin provider compared. The CDN bills its own delivery rate on all traffic; only cache misses (volume × (1 − hit ratio)) are pulled from the origin. A provider's own CDN is free or cheap to pull from; any other CDN pulls at that provider's internet egress rate.
• Fastly is a delivery network with no origin hosting, so its row is the cost of delivering the whole volume through Fastly and ignores the hit ratio. Cloudflare means R2 object storage with free egress.
• Each vendor's own meaning of a TB is used to turn your TB into GB (1,024 GB for AWS and Google Cloud, 1,000 for Azure, Cloudflare and Fastly). Every ladder is evaluated at that vendor's GB figure.
• Providers with no compute zones (Cloudflare, Fastly) have no cross-AZ or cross-region charge here, and their total is labelled egress only. Zero-egress storage still bills storage and operations, which are not in the total.
• AWS and Azure internet egress is priced by the region traffic leaves from: the data are AWS US East (N. Virginia) and Azure sources in North America and Europe.
• Where a vendor publishes no price above some volume (contact sales), the last published rate is carried forward and the result says so.

The data behind it

Three ways to reduce this number

1. Raise the CDN cache hit ratio: each 10 points of hit ratio removes 10% of the origin egress.
2. Serve large public objects from zero-egress storage or a CDN with no per-GB charge instead of straight from compute.
3. Keep chatty services in one availability zone where resilience allows it, and compress responses before they leave.

Use it from code

The same engine is available as a REST endpoint and as an MCP tool named calc_cloud_egress_bandwidth_calculator. Your scenario as an API call:

curl -X POST 'https://api.x12i.com/v1/calc/cloud-egress-bandwidth-calculator' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
  "input": {
    "current_provider": "aws",
    "monthly_outbound_tb": 50,
    "inter_az_pct": 0,
    "inter_region_pct": 0,
    "cdn": "none",
    "dest_na_eu_pct": 70,
    "dest_apac_pct": 20,
    "dest_other_pct": 10,
    "compare_providers": [
      "aws",
      "gcp",
      "azure",
      "cloudflare",
      "fastly"
    ]
  },
  "options": {
    "explain": false
  }
}'

Copy as API call Schema: GET /v1/calc/cloud-egress-bandwidth-calculator/schema

Frequently asked questions

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