GCP Cloud CDN cost: cache egress, cache fill, and lookups

Quick answer

Cloud CDN bills cache egress to users (tiered by region, roughly $0.08/GB in North America and Europe), cache fill when it fetches from the origin, and a small cache lookup fee per request. A high cache-hit ratio cuts both origin load and cost, since fewer requests trigger cache fill and origin work.

Cloud CDN caches content at Google's edge in front of a load balancer. Its bill has three parts, and the cache-hit ratio ties them together: the more you serve from cache, the less you pay for origin fetches and origin compute.

The three lines

Dimension	Rate (approximate)
Cache egress to users	~$0.08 / GB (NA/EU), tiered by region
Cache fill (origin fetch)	Per GB, by origin location
Cache lookup	~$0.0075 / 10k requests

Cache egress is the bytes delivered to users. Cache fill is what the CDN pays to pull content from your origin when it is not cached. Cache lookups are a tiny per-request fee. Egress usually dominates.

Hit ratio ties it together

Every cache miss triggers a cache fill from the origin and origin compute to generate the response, so a low hit ratio pays twice: fill cost plus origin load. Raising the hit ratio with sensible cache keys, longer TTLs on stable content, and cacheable responses reduces fill, origin cost, and latency at once, the same logic as CloudFront.

Reducing Cloud CDN cost

Maximize cache-hit ratio with good cache keys and TTLs, cache what is cacheable and avoid caching personalized responses, and keep the origin in a region with cheaper cache-fill rates. Because a CDN shifts egress off the origin and serves cached bytes cheaply, it usually lowers total cost, which is the caching-to-reduce-cost pattern at the edge.

FAQ

How is GCP Cloud CDN priced?

By cache egress to users (tiered by region, roughly $0.08 per GB in North America and Europe), cache fill when it fetches from the origin, and a small cache-lookup fee per request. Cache egress usually dominates the bill.

What is cache fill in Cloud CDN?

The cost of the CDN fetching content from your origin when it is not already cached, billed per gigabyte by origin location. Every cache miss triggers a fill, so a low cache-hit ratio increases fill cost as well as origin load.

How does cache-hit ratio affect Cloud CDN cost?

A higher hit ratio serves more from cache, so fewer requests trigger cache fill and origin compute. A low hit ratio pays twice, for fill and origin load, so raising the ratio with good cache keys and TTLs reduces cost and latency together.

How do I reduce Cloud CDN cost?

Maximize cache-hit ratio with sensible cache keys and longer TTLs on stable content, cache only cacheable responses (not personalized ones), and keep the origin where cache-fill rates are cheaper. A CDN generally lowers total cost by serving cached bytes cheaply.

Does a CDN lower my total GCP bill?

Usually, yes. Cloud CDN shifts egress off the origin, serves cached bytes at edge rates, and reduces origin compute on cache hits. For cacheable, read-heavy content the savings on origin load and egress typically exceed the CDN charges.

Does C3X estimate Cloud CDN cost?

Cloud CDN cost depends on egress, cache fill, and requests, which are usage inputs tied to traffic and hit ratio. C3X prices the surrounding infrastructure, and you model traffic and cache-hit ratio to estimate the CDN charges.

What to do next

Model your CDN before you ship it. C3X reads your Terraform and prices your resources against a live catalog. Start with the quickstart.