# Amazon DocumentDB serverless instance limits
<a name="docdb-serverless-instance-limits"></a>

For DocumentDB serverless instances, the following limits per instance are dependent upon the instance’s current scaling capacity:
+ Instance Memory (GiB)
+ Connections (all)
+ Cursor Limit
+ Open Transactions
+ Connections (active)

The following tables describe how the per-instance limits of serverless instances scale in relation to the instance’s current scaling capacity.

Note that the limit values are different depending on whether the cluster’s `MinCapacity` scaling configuration has been set to greater than two (2). If `MinCapacity` is set to less than or equal to 2, then the limit values for cursor limit, open transactions, and connections (active) are capped to a lower maximum value. (The technical reason for the cap is to support scaling down to an “idle” state. For more information, see [Idle state (0.5 DCUs)](docdb-serverless-how-it-works.md#docdb-serverlerss-idle-state).

**db.serverless instance limits if MinCapacity ≤1**


| Current Capacity (DCU) | Instance Memory (GiB) | Connections (all) | Cursor Limit | Open Transactions | Connections (active) | 
| --- | --- | --- | --- | --- | --- | 
|  0.5  |  1  |  250  |  6  |  12  |  39  | 
|  1  |  2  |  500  |  12  |  24  |  79  | 
|  2  |  4  |  1000  |  24  |  48  |  173  | 
|  4  |  8  |  2000  |  48  |  96  |  416  | 
|  8  |  16  |  4000  |  96  |  192  |  1071  | 
|  16  |  32  |  8000  |  132  |  264  |  1550  | 
|  32  |  64  |  16000  |  132  |  264  |  1550  | 
|  64  |  128  |  32000  |  132  |  264  |  1550  | 
|  128  |  256  |  60000  |  132  |  264  |  1550  | 
|  256  |  512  |  60000  |  132  |  264  |  1550  | 

**db.serverless instance limits if MinCapacity >1**


| Current Capacity (DCU) | Instance Memory (GiB) | Connections (all) | Cursor Limit | Open Transactions | Connections (active) | 
| --- | --- | --- | --- | --- | --- | 
|  1.5  |  3  |  7250  |  18  |  36  |  124  | 
|  2  |  4  |  1000  |  24  |  48  |  173  | 
|  4  |  8  |  2000  |  48  |  96  |  416  | 
|  8  |  16  |  4000  |  96  |  192  |  1071  | 
|  16  |  32  |  8000  |  192  |  384  |  2709  | 
|  32  |  64  |  16000  |  384  |  768  |  4500  | 
|  64  |  128  |  32000  |  768  |  1536  |  4500  | 
|  128  |  256  |  60000  |  1536  |  3072  |  4500  | 
|  256  |  512  |  60000  |  3072  |  6144  |  4500  | 

You can monitor and alarm on the per instance limits using the following CloudWatch metrics. For more on Amazon DocumentDB CloudWatch metrics, see [Monitoring Amazon DocumentDB with CloudWatch](cloud_watch.md).


| Resource | CloudWatch limit metric | CloudWatch usage metric (1-min. max) | CloudWatch usage metric | 
| --- | --- | --- | --- | 
| Instance Memory | - | - | FreeableMemory | 
| Connections (all) | DatabaseConnectionsLimit | DatabaseConnectionsMax | DatabaseConnections | 
| Cursors | DatabaseCursorsLimit | DatabaseCursorsMax | DatabaseCursors | 
| Transactions | TransactionsOpenLimit | TransactionsOpenMax | TransactionsOpen |