Cache Hit Rate
Definition
Measures the percentage of tokens used from cache. Cached tokens are significantly cheaper. A low cache hit rate signals an optimization opportunity for FinOps Practitioner and Engineering Personas .
Formula, as published
Cache Hit Rate = Cached Input Tokens / (Cached + Non-Cached Input Tokens) x 100
Calculate it
Example values to start with; replace them with yours.
How to measure it
Watch the input-token convention. OpenAI counts cached tokens inside input tokens; Anthropic counts cache reads on top. Divide cached tokens by all input tokens, cached and not.
On models that charge to write to the cache, a low hit rate can cost more than no caching at all.
Drop in your OpenAI or Claude usage export and see where the AI spend goes.
From the FinOps Foundation
More Usage Optimization KPIs
Definition and formula: Cache Hit Rate, FinOps KPI library, FinOps Foundation, licensed CC BY 4.0, read 16 Oct 2026. Changed: HTML removed, dashes and British spellings changed, formula split from its data sources and examples. The calculator and the notes are Finitizer’s.
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