| title | Azure Event Hubs Scalability Guide |
|---|---|
| description | Learn how to scale Azure Event Hubs effectively using partitions and throughput units. Discover strategies to handle increased workloads seamlessly. |
| ms.topic | concept-article |
| ms.date | 02/05/2026 |
There are two factors that influence scaling with Event Hubs.
- Throughput units (standard tier) or processing units (premium tier)
- Partitions
Throughput units control the throughput capacity of event hubs. Throughput units are prepurchased units of capacity. A single throughput unit provides the following capabilities:
- Ingress: Up to 1 MB per second or 1,000 events per second (whichever comes first).
- Egress: Up to 2 MB per second or 4,096 events per second.
If you exceed the capacity of the throughput units you purchased, ingress is throttled and Event Hubs throws a EventHubsException with a Reason value of ServiceBusy. Egress doesn't produce throttling exceptions, but it still can't go beyond the capacity of the throughput units you purchased. If you receive publishing rate exceptions or expect to see higher egress, check how many throughput units you purchased for the namespace. You can manage throughput units on the Scale page of the namespaces in the Azure portal. You can also manage throughput units programmatically by using the Event Hubs APIs.
You prepurchase throughput units and pay for them by the hour. Once you purchase throughput units, you pay for a minimum of one hour. You can purchase up to 40 throughput units for an Event Hubs namespace, and all event hubs in that namespace share these throughput units. All partitions and consumers within each event hub share the total ingress and egress capacity of these throughput units, so multiple consumers reading from the same partition share the available bandwidth.
The Auto-inflate feature of Event Hubs automatically scales up by increasing the number of throughput units to meet usage needs. Increasing throughput units prevents throttling scenarios, in which:
- Data ingress rates exceed set throughput units.
- Data egress request rates exceed set throughput units.
The Event Hubs service increases the throughput when load increases beyond the minimum threshold, without any requests failing with ServerBusy errors.
For more information about the autoinflate feature, see Automatically scale throughput units.
Event Hubs Premium provides superior performance and better isolation within a managed multitenant PaaS environment. The resources in a Premium tier are isolated at the CPU and memory level so that each tenant workload runs in isolation. This resource container is called a Processing Unit (PU). You can purchase 1, 2, 4, 6, 8, 10, 12, or 16 processing Units for each Event Hubs Premium namespace.
How much you can ingest and stream with a processing unit depends on various factors such as your producers, consumers, the rate at which you're ingesting and processing, and much more.
For example, Event Hubs Premium namespace with one PU and one event hub (100 partitions) can approximately offer core capacity of ~5-10 MB/s ingress and 10-20 MB/s egress for both AMQP or Kafka workloads.
For more information about configuring PUs for a premium tier namespace, see Configure processing units.
Note
For more information about quotas and limits, see Azure Event Hubs - quotas and limits.
[!INCLUDE event-hubs-partitions]
To learn more about Event Hubs, see the following articles:
