> For the complete documentation index, see [llms.txt](https://docs-v4.venus.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-v4.venus.io/technical-reference/reference-isolated-pools/interest-rate-models/interest-rate-model.md).

# InterestRateModel

The current [`InterestRateModel`](https://github.com/VenusProtocol/isolated-pools/blob/v4.4.0/contracts/InterestRateModel.sol) interface exposes three functions. Rates are mantissas scaled by `1e18` and are returned per slot, where the implementation defines a slot as a block or one second.

## `getBorrowRate`

```solidity
function getBorrowRate(
    uint256 cash,
    uint256 borrows,
    uint256 reserves,
    uint256 badDebt
) external view returns (uint256);
```

Returns the borrow rate per slot. Current model implementations calculate utilization from `(borrows + badDebt) / (cash + borrows + badDebt - reserves)` and cap utilization at `1e18`.

## `getSupplyRate`

```solidity
function getSupplyRate(
    uint256 cash,
    uint256 borrows,
    uint256 reserves,
    uint256 reserveFactorMantissa,
    uint256 badDebt
) external view returns (uint256);
```

Returns the supplier rate per slot after applying the reserve factor. Supply-rate income is based on performing borrows; bad debt affects utilization and the denominator but is not multiplied into `incomeToDistribute`.

## `isInterestRateModel`

```solidity
function isInterestRateModel() external pure returns (bool);
```

Returns `true` as a compatibility marker.

The interface does not expose the clock. Current implementations inherit `isTimeBased()` and `blocksOrSecondsPerYear()` from `TimeManagerV8`; read those functions from the deployed model before annualizing a rate.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs-v4.venus.io/technical-reference/reference-isolated-pools/interest-rate-models/interest-rate-model.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.