LLM Error Rate
Usage OptimizationAnomaly ManagementReporting & AnalyticsKPIs & BenchmarkingAI
Definition
Measures the error rate for failed LLM calls. This is a direct proxy for retry waste since tokens are still consumed. A high error rate signals an optimization opportunity for FinOps Practitioner and Engineering Personas .
Formula, as published
LLM Error Rate = Failed LLM Spans / Total LLM Spans x 100
- Where:
- A “span” is a granular monitoring technique that breaks down an agent’s execution into specific internal segments that can be used to track the multiple-reasoning steps used by an agent. It is the building block of a trace.
Calculate it
Example values to start with; replace them with yours.
LLM error rate
1.5%
From the FinOps Foundation
More Usage Optimization KPIs
Definition and formula: LLM Error 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.
Measured once, a KPI is a number. Tracked daily, it is a practice.
Finitizer computes the KPIs your billing data supports every day, by team and product, across AWS and Google Cloud.
See how Finitizer works