azure cosmos db for mongo db pricing

Iheb Jendoubi 60 Reputation points
2025-03-17T13:11:09.6233333+00:00

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I'm using Cosmos DB with the MongoDB API and have provisioned my database with 2800 RU/s (with 100 RU/s free). Each collection is allocated 400 RU/s. Could someone explain what 400 RU/s actually means in practical terms? For example, if I have a 4KB document that costs around 4 RU per read, does that imply I can perform roughly 100 requests per second on that collection? Additionally, how is the pricing calculated based on this provisioned throughput? The available documentation isn't very clear on these details. Any clarification would be greatly appreciated!

And can smeone explain to me the 7562.5/2976 from where they comes?

Azure Cosmos DB
Azure Cosmos DB
An Azure NoSQL database service for app development.
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  1. Saraswathi Devadula 5,570 Reputation points Microsoft External Staff Moderator
    2025-03-18T09:19:05.5233333+00:00

    Hello Iheb Jendoubi

    Greetings!

    As I understand, you want to know about the Azure Cosmos DB billing. Please review the information below for a better understanding:

    What 400 RU/s means:

    • RU/s (Request Unit per Second) is a measure of throughput in Azure Cosmos DB. It quantifies the processing power needed to perform operations (reads, writes, queries) on your database.
    • 400 RU/s means you have a guaranteed capacity to perform operations that consume up to 400 Request Units in one second.
    • The pricing for Azure Cosmos DB is based on the provisioned throughput and storage, which is measured in RU/s.
    • If a 4KB document read costs 4 RU, then with 400 RU/s, you could theoretically perform around 100 reads per second (400 RU/s divided by 4 RU per read = 100 reads per second).

    Note:

    • Different operations have different RU costs (writes are typically more expensive than reads).
    • Document size, indexing, query complexity, and other factors affect RU consumption.

    **
    Pricing based on Provisioned Throughput:

    • Cosmos DB pricing is primarily based on the provisioned throughput (RU/s). You pay for the capacity you reserve, regardless of whether you fully utilize it.
    • The cost is typically calculated on an hourly basis.
    • Formula: Cost = (Provisioned RU/s) x (Hourly rate per RU) x (Number of hours)
    • There are also costs associated with data storage, but the RU/s is the main driver of cost.

    I hope this has been helpful!

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    Thank you.

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