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Digital Infrastructure

CDN Origin Egress Offload Calculator

How much origin egress and transfer spend does a byte-weighted CDN hit ratio avoid?

Measured values and planning assumptions
Supported: 0 to 1000000000.
Supported: 0 to 100.
Supported: 0 to 1000.
Supported: 0 to 1000.
Supported: 0 to 1000000000.

Method, formula and assumptions

Origin GB = delivery GB x byte miss fraction. CDN case spend = origin GB x origin price + all delivery GB x edge price + fixed fee. Difference subtracts origin-only spend.

Input definitions and supported units

  • Monthly delivered bytes (GB): Measured or assumed numerical value, from 0 to 1000000000; zero is supported where the stated method permits it.
  • Byte hit ratio (%): Measured or assumed numerical value, from 0 to 100; zero is supported where the stated method permits it.
  • Origin egress price (currency/GB): Measured or assumed numerical value, from 0 to 1000; zero is supported where the stated method permits it.
  • Edge delivery price (currency/GB): Measured or assumed numerical value, from 0 to 1000; zero is supported where the stated method permits it.
  • Monthly fixed CDN charge: Measured or assumed numerical value, from 0 to 1000000000; zero is supported where the stated method permits it.

Worked example with answer

10,000 GB at 80% byte hits leaves 2,000 GB origin egress and avoids 8,000 GB. At 0.08 origin, 0.02 edge and 50 fixed, spend is 410 versus 800 origin-only: a -390 difference.

How to use the results

A negative difference is modeled savings. Use byte hit ratio rather than request hit ratio when large and small assets differ.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Prices are your inputs, not provider quotes. Excludes regional tiers, request charges, origin-fill billing, taxes and free allowances.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

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