KBY Engineering Utilities

Kafka / Event Stream Partition Calculator

Calculate the theoretical partition minimum for a throughput target using benchmarked per-partition producer and consumer rates.

Accuracy contract: The max(target/producer, target/consumer) arithmetic is deterministic, but it is only a throughput lower bound and depends on representative benchmarks.

Inputs

Defined calculation contract

Target throughput (MB/s)The total peak bandwidth the topic needs to process.Single producer speed (MB/s)The maximum throughput a single producer instance can push to a partition.Single consumer speed (MB/s)The maximum throughput a single consumer instance can read and process from a partition.

Exact output

Calculation result

500 MB/s

Target throughput

50 MB/s

Producer speed

20 MB/s

Consumer speed

Min partitions (Producer)

Min partitions (Consumer)

Throughput minimum

Planning result

The throughput formula gives a minimum of 25 partitions for the supplied 500 MB/s target. It is not a complete topic-sizing recommendation.

Use benchmarked per-partition producer and consumer rates. Then separately check key skew, ordering requirements, consumer-group concurrency, replication, broker limits, failure recovery, and expected growth before choosing the final count.

Versioned sources

Confluent: How to choose the number of partitions

Deterministic v2026.08.1 — Advanced · 2 min