# 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 |