# Cosmos DB

## Azure Cosmos DB — commitment brief

> **Data sourced**: March 2026. Verify current figures at the [Azure Pricing Calculator](https://azure.microsoft.com/en-us/pricing/calculator/).

### Coverage summary

Azure Cosmos DB supports reserved capacity in RU/s (Request Units per second) increments, applicable across all Cosmos DB APIs — NoSQL, MongoDB, Cassandra, Gremlin, and Table. Discounts scale with reservation size: small reservations (100 RU/s units) save 20–30%, while large-scale commitments (30M+ multi-master RU/s) can reach up to \~63% off pay-as-you-go. Serverless accounts are not eligible for reservations. Cosmos DB is also covered by the Azure Database Savings Plan (1-yr only) as a flexible alternative.

**What is covered**: Provisioned throughput costs (RU/s), across both single-region write and multi-region write (multi-master) configurations. Reservation discount applies automatically across all Cosmos DB databases and containers in the reservation scope.

**What is not covered**: Storage (billed per GB), networking/egress, Serverless accounts, throughput consumed above the reserved amount (billed at pay-as-you-go). Autoscale accounts use a 1.5x RU/s multiplier — a 100,000 RU/s reservation covers approximately 66,667 RU/s of autoscale capacity.

### Azure Hybrid Benefit

> Not applicable. Cosmos DB is a fully managed PaaS database with no underlying OS or SQL Server license. AHB is not available for this service.

### SKU / tier coverage

| SKU / Tier                      | Reservation | Savings Plan  | 1-yr discount | 3-yr discount | Notes                                                             |
| ------------------------------- | ----------- | ------------- | ------------- | ------------- | ----------------------------------------------------------------- |
| 100 RU/s — Single-region write  | ✅ Yes       | ✅ Yes (DB SP) | 20%           | 30%           | Base unit; up to 999,900 RU/s in 100-unit increments              |
| 100 RU/s — Multi-master         | ✅ Yes       | ✅ Yes (DB SP) | 20%           | 30%           | Multi-region write configuration                                  |
| 1,000,000 RU/s — Single-region  | ✅ Yes       | ✅ Yes (DB SP) | 27%           | \~40%         | Progressive discount tier                                         |
| 1,000,000 RU/s — Multi-master   | ✅ Yes       | ✅ Yes (DB SP) | 32%           | \~45%         |                                                                   |
| 5,000,000 RU/s — Single-region  | ✅ Yes       | ✅ Yes (DB SP) | \~35%         | \~50%         |                                                                   |
| 5,000,000 RU/s — Multi-master   | ✅ Yes       | ✅ Yes (DB SP) | \~40%         | \~55%         |                                                                   |
| 10,000,000 RU/s — Single-region | ✅ Yes       | ✅ Yes (DB SP) | \~40%         | \~55%         |                                                                   |
| 10,000,000 RU/s — Multi-master  | ✅ Yes       | ✅ Yes (DB SP) | \~45%         | \~60%         |                                                                   |
| 30,000,000 RU/s — Multi-master  | ✅ Yes       | ✅ Yes (DB SP) | \~48%         | \~63%         | Maximum discount tier                                             |
| Serverless accounts             | ❌ No        | ✅ Yes (DB SP) | —             | —             | Not eligible for RU/s reservations; Database Savings Plan applies |

### Reservation vs. Azure Database Savings Plan

**Reservation**: Scoped to a specific RU/s quantity and write configuration (single vs. multi-master). Delivers the highest discount, scaling up to \~63% at 3-yr for large multi-master deployments. Discount applies automatically across all Cosmos DB APIs in scope — no per-API selection needed. Best for stable, provisioned-throughput workloads with predictable RU/s usage.

**Azure Database Savings Plan** *(1-yr only)*: Hourly spend commitment covering Cosmos DB, Azure SQL Database, Azure SQL Managed Instance, Azure Database for PostgreSQL, and other eligible managed databases. Flexible — applies across regions and database engines automatically. Covers Serverless accounts (unlike reservations). Up to \~35% savings vs. pay-as-you-go. Best for mixed database estates or Serverless workloads.

## Regional availability

Azure Cosmos DB reserved capacity can be applied across all Azure regions. When you purchase a Cosmos DB reservation, it functions as a monetary credit that covers provisioned throughput costs across all regions where your Cosmos DB resources run — discounts apply automatically in each region at the ratio equivalent to that region's on-demand pricing. You do not need a separate reservation per region.

**Notable exclusions**: Azure Government and Azure China regions are not supported for Cosmos DB reservations. Serverless accounts are not eligible for RU/s reservations in any region (use the Azure Database Savings Plan instead).

⚠️ Availability varies by SKU and region. Always verify in the [Azure portal](https://portal.azure.com) or via the [Azure Retail Pricing API](https://prices.azure.com/api/retail/prices) before purchasing.

### Archera

Azure Cosmos DB is within Archera's commitment management scope. Archera can automate RU/s reservation purchase across APIs, monitor throughput utilization, and wrap commitments in a GRI/GSP — eliminating downside risk on over-committed provisioned throughput.

***

**Sources**

* [Optimize cost with reserved capacity in Azure Cosmos DB](https://learn.microsoft.com/en-us/azure/cosmos-db/reserved-capacity)
* [Announcing savings plan for databases](https://techcommunity.microsoft.com/blog/finopsblog/announcing-savings-plan-for-databases-flexible-savings-for-modern-evolving-workl/4503107)
* [What are Azure savings plans?](https://learn.microsoft.com/en-us/azure/cost-management-billing/savings-plan/savings-plan-overview)
* [Azure Cosmos DB pricing](https://azure.microsoft.com/en-us/pricing/details/cosmos-db/)

⚠️ Discount percentages shown are from published Microsoft documentation and vary by RU/s size and write configuration. Always verify with the [Azure Pricing Calculator](https://azure.microsoft.com/en-us/pricing/calculator/).