# Throughput Units Left Inflated After Event Hubs Auto-Inflate Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/throughput-units-left-inflated-after-event-hubs-auto-inflate On the Event Hubs Standard tier, capacity is bought in throughput units (TUs), and auto-inflate raises the TU count automatically when ingress or... By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version On the Event Hubs Standard tier, capacity is bought in throughput units (TUs), and auto-inflate raises the TU count automatically when ingress or egress approaches the current limit. PointFive Research Cloud cost research at PointFive Azure service [Azure Event Hubs](https://www.pointfive.co/efficiency-hub/cloud-services/azure-event-hubs) Category [Other](https://www.pointfive.co/efficiency-hub/service-category/other) Reference CER-0453 Type Overprovisioned Resource ## Explanation Why the waste happens and who it affects. Auto-inflate only scales up. Microsoft documents that it does not scale TUs back down when traffic drops, so after a one-off spike, a backfill, a replay or a load test the namespace stays at the higher TU count and is billed for it every hour until someone lowers it. Because auto-inflate is usually enabled precisely so that nobody has to watch capacity, the ratchet goes unnoticed. Over months a namespace can drift to its configured maximum even though normal traffic needs a fraction of that. Teams running many namespaces, or namespaces with Capture enabled, feel it most, since Capture on Standard is also charged per TU. ## Billing model The pricing dimensions that drive this cost. Standard tier capacity is billed per throughput unit per hour, independent of how much of that capacity is used. Throughput unit Billed hourly based on the maximum number of TUs selected during the hour; each TU allows up to 1 MB/s or 1,000 events per second of ingress and 2 MB/s of egress for the namespace Ingress events Billed separately per million events on Basic and Standard, regardless of TU count Capture on Standard Billed hourly per purchased throughput unit, so inflated TUs also raise the Capture charge Auto-inflate maximum The upper TU limit auto-inflate may reach; the limit itself costs nothing, only the TUs actually in place each hour are billed ## How to detect 5 checks to find it in your estate. - List Standard namespaces with auto-inflate enabled (isAutoInflateEnabled true) and compare the current TU capacity (sku.capacity) with maximumThroughputUnits; namespaces sitting at or near the maximum deserve review - Chart IncomingBytes, IncomingMessages and OutgoingBytes at the namespace level over several weeks and compare peak per-second rates with the per-TU limits; sustained use far below the current TU allowance indicates excess TUs - Check ThrottledRequests and Quota Exceeded Errors to confirm that a lower TU count would not have caused throttling at recent peaks - Enable the autoscale logs diagnostic category (AZMSAutoscaleLogs table) to see each inflate action with the previous and new TU values and what triggered it; a step up with no later step down marks a ratchet - In Cost Management, group Event Hubs cost by resource and meter to find namespaces whose throughput unit charge has stepped up and stayed flat ## How to fix 5 ways to remove the waste. - Manually lower the TU count on the namespace Scale page (or by updating sku.capacity) to what recent peaks require, leaving headroom; auto-inflate will raise it again if traffic genuinely grows - Automate scale-down with an Azure Automation runbook or an Azure Function triggered by metric alerts or a schedule, as the Well-Architected guide for Event Hubs suggests - Set the auto-inflate maximum from a budget and capacity plan rather than leaving it at a high value, and use Azure Policy to cap TUs where appropriate - Before planned backfills or load tests, record the TU count and restore it afterwards - For development and test namespaces, use Basic or Standard with minimal TUs and shorter retention ## Documentation Vendor references for pricing and configuration. - [Auto inflate in Azure Event Hubs learn.microsoft.com](https://learn.microsoft.com/en-us/azure/event-hubs/event-hubs-auto-inflate) - [Pricing - Event Hubs azure.microsoft.com](https://azure.microsoft.com/en-us/pricing/details/event-hubs/) - [Architecture Best Practices for Azure Event Hubs - Microsoft Azure Well-Architected Framework learn.microsoft.com](https://learn.microsoft.com/en-us/azure/well-architected/service-guides/azure-event-hubs) - [Monitoring data reference for Azure Event Hubs learn.microsoft.com](https://learn.microsoft.com/en-us/azure/event-hubs/monitor-event-hubs-reference) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - Microsoft Fabric CER-0337 ### [Oversized Microsoft Fabric Capacity During Low-Utilization Periods](https://www.pointfive.co/efficiency-hub/inefficiencies/oversized-microsoft-fabric-capacity-during-low-utilization-periods) Microsoft Fabric capacity is billed based on the provisioned SKU tier (F2, F4, F8, F16, F64, etc.) on an hourly basis, regardless of whether workloads are actively consuming those resources. Each SKU tier provides a fixed pool of Capacity... Other - Azure Container Registry CER-0329 ### [Overprovisioned or Idle Azure Container Registry Tier](https://www.pointfive.co/efficiency-hub/inefficiencies/overprovisioned-or-idle-azure-container-registry-tier) Azure Container Registry charges a fixed daily fee based on the selected tier - Basic, Standard, or Premium - regardless of whether the registry is actively used. This means a registry with zero image pulls, zero pushes, and no active... Other - Azure Logic Apps CER-0309 ### [Idle or Untriggered Azure Logic Apps Generating Continuous Charges](https://www.pointfive.co/efficiency-hub/inefficiencies/idle-or-untriggered-azure-logic-apps-generating-continuous-charges) Azure Logic Apps can quietly accumulate costs even when no workflows are actively executing, but the mechanism differs significantly depending on the deployment model. In the Consumption (multitenant) plan, Logic Apps with polling triggers... Other --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.