# getRateLiquidityDepthByPair

This function is used to calculate the amount of liquidity that exists for a specific pair up to the specified exchange rate. 

```
public async getRateLiquidityDepthByPair(
    sourceToken: string,
    targetToken: string,
    rate: string
  )
```

<table><thead><tr><th width="160.33333333333331">Name</th><th>Type</th><th>Description</th></tr></thead><tbody><tr><td>sourceToken</td><td>token address</td><td>The token being sold.</td></tr><tr><td>targetToken</td><td>token address</td><td>The token being bought. </td></tr><tr><td>rate</td><td>string (number)</td><td>The number of target tokens per base token.</td></tr></tbody></table>

### Returns

This function returns a **string** with the amount of liquidity available at the specified rate.&#x20;