Glossary

Consumer offset (Kafka)

A Kafka consumer offset is the position in a partition log that a consumer group has committed as successfully processed. It represents the next message the consumer will read on restart — not the last message read. Offsets are stored in the internal `__consumer_offsets` topic. The gap between log end offset and committed offset is consumer lag.

Formula: Lag ≈ log_end_offset − committed_offset (per partition).

Last updated: March 2026