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CDN Edge Distribution Calculator

Split CDN load across points of presence and check the origin request rate and egress that survives the cache hit ratio.

About CDN Edge Distribution Calculator

Anycast routing spreads requests roughly evenly across points of presence, and everything the edge can answer never reaches the origin. The miss fraction is what determines origin sizing, and because it multiplies the full object size it dominates origin egress cost. Cache hit ratio has brutal leverage on origin load: dropping from 95% to 90% doubles the requests hitting your origin, which is why cache-key and TTL design is a capacity decision, not a tuning detail.

Formula

CDN Edge Distribution

requests per PoP = total ÷ PoPs; origin requests = total × (1 − cache hit ratio); egress = request rate × object size × 8.

hit
Fraction of requests answered from the edge cache
originEgress
Bandwidth the origin must still serve for cache misses and revalidation

Worked example

With the default values below, CDN Edge Distribution Calculator returns Requests per PoP of 6,250. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total requests per secondaccepts 1–100,000,000 rps
250,000 rps
Points of presenceaccepts 1–5,000 PoPs
40 PoPs
Edge cache hit ratioaccepts 0–100 %
92 %
Average object sizeaccepts 0.1–1,000,000 KB
180 KB
Origin capacityaccepts 1–10,000,000 rps
5,000 rps

Results

Requests per PoP
6,250 rps
Requests Reaching the Origin
20,000 rps
Origin Utilisation
400.0%
Edge Egress
339.15 Gbps
Origin Egress
29.49 Gbps
Traffic Offloaded from the Origin
92.0%

Step by step

  1. 1Values used
  2. 2CDN Edge Distribution
  3. 3Requests per PoP= 6,250 rps
  4. 4Requests Reaching the Origin= 20,000 rps
  5. 5Origin Utilisation= 400.0
  6. 6Edge Egress= 339.15 Gbps
  7. 7Origin Egress= 29.49 Gbps
  8. 8Traffic Offloaded from the Origin= 92.0

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is CDN Edge Distribution calculated?

requests per PoP = total ÷ PoPs; origin requests = total × (1 − cache hit ratio); egress = request rate × object size × 8. Anycast routing spreads requests roughly evenly across points of presence, and everything the edge can answer never reaches the origin. The miss fraction is what determines origin sizing, and because it multiplies the full object size it dominates origin egress cost.

Why does CDN Edge Distribution matter?

Cache hit ratio has brutal leverage on origin load: dropping from 95% to 90% doubles the requests hitting your origin, which is why cache-key and TTL design is a capacity decision, not a tuning detail.

What values do I need to enter?

This calculator takes 5 inputs: Total requests per second, Points of presence, Edge cache hit ratio, Average object size, Origin capacity. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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