> ## Documentation Index
> Fetch the complete documentation index at: https://docs.derive.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Interest Rate Model

| Parameter     | Contract Variable                        | Value | Description                                                                                                                       |
| ------------- | ---------------------------------------- | ----- | --------------------------------------------------------------------------------------------------------------------------------- |
| MIN\_RATE     | \`lending\_pools.irm.min\_rate\`         | 0     | The borrow rate at zero utilization.                                                                                              |
| OPTIMAL\_UTIL | \`lending\_pools.irm.optimal\_util\`     | 0.80  | The kink in the curve. Above it the rate rises far more steeply.                                                                  |
| LOW\_SLOPE    | \`lending\_pools.irm.rate\_at\_optimal\` | 0.048 | The borrow rate reached at \`OPTIMAL\_UTIL\`, i.e. 4.8% at 80% utilization.                                                       |
| HIGH\_SLOPE   | \`lending\_pools.irm.rate\_at\_full\`    | 1.0   | The additional rate charged between \`OPTIMAL\_UTIL\` and full utilization, so 104.8% at 100%.                                    |
| SM\_FEE       | \`lending\_pools.irm.sm\_interest\_fee\` | 20%   | Share of interest paid by borrowers that is diverted to the Security Module. Rises to 100% while the Security Module is depleted. |


## Related topics

- [public/get_interest_rate_history](/api-reference/market-data/publicget_interest_rate_history.md)
- [Rate Limits for Integrators and Market Makers](/integrators/trading/rate-limits.md)
- [Rate Limits](/rate-limits.md)