Azure Reserved Capacity for SQL and Cosmos DB Explained

Last updated: June 2026

Written by Fredrik Filipsson and reviewed by Morten Andersen. Method: See, Cut, Lock, Run. We have optimized $420M+ in cloud spend across 500+ environments.

Azure reserved capacity for databases is a billing commitment that discounts the steady compute or throughput a database consumes in exchange for a one or three year term. For Azure SQL Database it discounts the vCore compute; for Azure Cosmos DB it discounts provisioned throughput measured in request units per second. Because production databases run continuously and rarely scale to zero, they are among the safest things in a cloud estate to commit. This article is part of our Azure cluster; start with the complete guide to Azure cost optimization, the pillar this piece links up to. Buying these commitments is a Lock step in our See, Cut, Lock, Run method, applied after rightsizing the databases, not before.

How much does Azure SQL Database reserved capacity save?

Azure SQL Database reserved capacity saves up to about 33% on compute versus license-included pay-as-you-go. The discount scales with the term: a one-year General Purpose vCore commitment runs around 21% and a three-year commitment around 33%, per Microsoft's SQL Database reservations documentation. The reservation covers the vCore compute only; licensing, storage, and I/O are billed separately. If you hold SQL Server licenses with Software Assurance, you can layer Azure Hybrid Benefit on top of the reservation, and the two together push total savings up to about 80% versus full pay-as-you-go. That stacking is the single largest database-cost lever on Azure.

How much does Azure Cosmos DB reserved capacity save?

Azure Cosmos DB reserved capacity discounts provisioned throughput by a minimum of about 20% and up to roughly 63% on the largest reservations. The discount applies to provisioned throughput measured in request units per second (RU/s), and the deepest tiers reward very large commitments above one million RU/s, per Microsoft's Cosmos DB reserved capacity documentation. It covers provisioned throughput only, not storage and not serverless consumption, so the reservation should be sized to the steady RU/s floor your databases and containers always run at. Like every reservation, it is use-it-or-lose-it, so under-committing slightly and letting pay-as-you-go cover the variable top is safer than over-committing.

What does the reservation not cover?

Reserved capacity covers the compute or throughput baseline and nothing else, which is the detail that decides whether the savings math holds. For SQL Database, that means licensing, storage, backup, and I/O remain at standard rates. For Cosmos DB, that means storage and any serverless usage remain at standard rates, and only provisioned throughput is discounted. Sizing a reservation as if it covered the whole database bill is the most common mistake, and it leads to buying too large. Reserve only the part the discount actually touches.

When should you buy database reserved capacity?

Buy when the database runs continuously at a predictable baseline, which is the normal state for production SQL and Cosmos workloads. The reservation rewards exactly that steady, always-on consumption, so a production database you will keep for the next year or three is a textbook candidate. Hold off when the workload is being rightsized, migrated, or retired, when usage is volatile, or when you have not yet trimmed over-provisioned vCores or RU/s. The order is rightsize first, then reserve the clean baseline, because committing before rightsizing locks in the over-provisioning. We apply the same sequencing to storage in Azure Blob Storage reserved capacity explained.

Can you combine reserved capacity with Azure Hybrid Benefit?

Yes, for SQL Database, and stacking them is how the savings reach their peak. Reserved capacity discounts the compute through the term commitment, while Azure Hybrid Benefit applies SQL Server licenses you already own under Software Assurance instead of paying license-included rates. The two operate on different parts of the bill, so they combine rather than conflict, and together they take SQL savings up to about 80% versus full pay-as-you-go. Cosmos DB does not use Hybrid Benefit, so there the lever is reserving the right RU/s after autoscale and rightsizing have set the baseline. Both fit inside the broader commitment strategy covered in the Azure cost optimization pillar.

Discount percentages, coverage scope, and the Hybrid Benefit interaction reflect Azure as of June 2026. Verify the current rates for your service tier, region, and term in the linked Azure documentation before committing, because database pricing and reservation terms change.

Frequently asked questions

The short version

Azure reserved capacity discounts the steady compute and throughput your databases always consume: up to about 33% on SQL Database vCores, up to about 80% when stacked with Hybrid Benefit, and up to roughly 63% on Cosmos DB provisioned throughput. Rightsize first, reserve only the covered baseline, and let pay-as-you-go absorb the variable layer. When you want the databases rightsized and the reservations sized in one pass, that is exactly what our Azure cost optimization service delivers.