# Request Unit (RU)

|Resource Type|RU consumption                           |
|:------------|:----------------------------------------|
|Read         |2 storage read batches consume 1 RU      |
|             |8 storage read requests consume 1 RU     |
|             |64 KiB read request payload consumes 1 RU|
|Write        |1 storage write batch consumes 1 RU      |
|             |1 storage write request consumes 1 RU    |
|             |1 KiB write request payload consumes 1 RU|
|SQL CPU      |3 ms consumes 1 RU                       |

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+ Each write operation is eventually replicated to all replicas (by default, TiKV has 3 replicas). Each replication operation is considered a different write operation.
+ In addition to queries executed by users, RU can be consumed by background tasks, such as automatic statistics collection.
+ The preceding table lists only the resources involved in RU calculation for TiDB Self-Hosted clusters, excluding the network and storage consumption. For TiDB Serverless RUs, see TiDB Serverless Pricing Details.