Issue
I set a traces sample rate, for example 0.1 (10%), but the ratio of accepted to dropped transactions in my Sentry stats does not match that percentage. I expected roughly 10% of my transactions to be sent and the numbers look off.
Applies To
All SaaS Customers and Self-Hosted Users
Filtering and Sampling
All SDKs
Resolution
tracesSampleRate does not apply to your total transaction volume. With a rate of 0.1, Sentry does not send exactly 1 out of every 10 transactions. Instead, Sentry applies the rate to each transaction individually, so every transaction has a 10% chance of being kept.
If Sentry keeps more or fewer transactions than you expect, check these factors, ordered by how often they explain the mismatch:
Volume: lower
tracesSampleRateto reduce the number of accepted transactions.Decision precedence: in distributed tracing, the sampling decision is made once at the head of the trace and propagates to downstream services, so an upstream service can decide whether the whole trace is kept.
Cached or older app versions: users on a previous release may still send transactions at an old
tracesSampleRate.