Practical guide
Estimate Cloud CDN cost from hits and misses
Forecast Cloud CDN from cache delivery, lookup requests, cache fill, destinations, and the origin path on misses.
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Price delivery, lookup, and fill
Google describes Cloud CDN cacheable-hit charges as cache lookup plus cache data transfer out. A cacheable miss adds cache fill and applicable origin charges. Delivery prices vary by destination and usage tier, so split traffic by destination rather than use one worldwide number.
For example, 10,000 GiB delivered at a 90% hit ratio implies 9,000 GiB hit delivery and roughly 1,000 GiB cache-fill quantity before considering response behavior. If there are 50 million GET or HEAD requests, add 50 million lookup requests. Apply current regional/destination rates to each line; this is a usage model, not a price quote.
The origin may still incur Load Balancing, Cloud Storage operations, or Compute Engine transfer charges on misses. Use the Cloud CDN Cost Calculator for North America delivery, within-region fill, and lookup assumptions, then model the origin separately.
FAQ
Are POST requests cache lookups?
Google lists GET and HEAD as lookup-causing methods; check the current documentation for behavior.
Does a high hit ratio eliminate all CDN cost?
No. Cache delivery and lookup charges still apply.