Why can't I change partition count after creating an Event Hub?

Partitions determine the physical data layout and consumer parallelism. Changing the count would require redistributing all data and breaking consumer offset tracking. For this reason, Azure locks partition count at creation time (though Premium/Dedicated tiers now support scaling up). Choose carefully using this calculator.

What is the relationship between partitions and throughput units?

Each throughput unit (TU) provides 1 MB/s ingress and 2 MB/s egress. Partitions determine the number of parallel consumers. You need enough TUs for total throughput and enough partitions for consumer parallelism. A common starting point is to match partition count to expected peak consumer instances.

Azure Event Hub Partition Calculator

ServerlessAzure

Calculate partition count, throughput units, and consumer group layout.

Event Hub Parameters

Ingress Rate (MB/s)

Avg Event Size (bytes)

Consumer Groups

Processing Latency (ms)

1 Throughput Unit (TU) = 1 MB/s ingress, 2 MB/s egress, up to 1,000 events/s ingress.

Raw Output

Output will appear here...

About This Tool

The Azure Event Hub Partition Calculator helps you determine the optimal number of partitions and throughput units for your Azure Event Hubs deployment. Partition count directly affects parallelism and throughput capacity, and it cannot be changed after creation. This tool calculates recommendations based on your expected message rate, message size, consumer count, and processing requirements, helping you make an informed decision before provisioning.

When to Use This Tool

•Calculate the required number of partitions and throughput units for a new Event Hub based on expected ingestion rate.
•Determine whether to scale up throughput units or increase partitions when approaching capacity limits.
•Plan Event Hub sizing for high-volume IoT telemetry, application logging, or real-time analytics workloads.
•Compare Standard and Premium tier capacity to choose the right SKU for your throughput requirements.

Frequently Asked Questions

Why can't I change partition count after creating an Event Hub?: Partitions determine the physical data layout and consumer parallelism. Changing the count would require redistributing all data and breaking consumer offset tracking. For this reason, Azure locks partition count at creation time (though Premium/Dedicated tiers now support scaling up). Choose carefully using this calculator.
What is the relationship between partitions and throughput units?: Each throughput unit (TU) provides 1 MB/s ingress and 2 MB/s egress. Partitions determine the number of parallel consumers. You need enough TUs for total throughput and enough partitions for consumer parallelism. A common starting point is to match partition count to expected peak consumer instances.

Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.