> For the complete documentation index, see [llms.txt](https://docs.kpk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kpk.io/funds/infrastructure/onchain-accounting/price-feeds/cbeth.md).

# cbETH

cbETH is Coinbase's wrapped staked-ETH token. No direct cbETH/USD Chainlink feed is used; this `ICustomPriceFeed` adapter combines the token's own exchange rate with an ETH/USD price read from the NAV's own primary feed.

{% hint style="warning" %}
**This feed is built and tested but deployed on no chain.** Mainnet cbETH is not a held asset, so it is not registered on any NAV Calculator. cbETH **is** priced on Base, by the separate [cbETH (L2)](/funds/infrastructure/onchain-accounting/price-feeds/cbeth-l2.md) feed — a different composition, using a Chainlink cbETH/ETH market rate.

The contract is kept deliberately rather than deleted: it reads cbETH's own `exchangeRate()`, which is **fundamental** and therefore independent of the market feed the L2 variant composes — exactly the shape a divergence monitor needs, should mainnet cbETH ever be held.
{% endhint %}

{% hint style="info" %}
The ETH/USD term is sourced from the NAV's own selector — see [Base/USD from the NAV's own selector](/funds/infrastructure/onchain-accounting/price-feeds.md#base-usd-from-the-navs-own-selector).
{% endhint %}

**Source:** [`cbETH_CustomPriceFeed.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/prices/protocols/cbETH_CustomPriceFeed.sol)

{% hint style="info" %}
**Mainnet feed.** The L2 deployments use a different oracle composition — see [cbETH (L2)](/funds/infrastructure/onchain-accounting/price-feeds/cbeth-l2.md).
{% endhint %}

***

## Approach

`exchangeRate()` × ETH/USD.

<figure><img src="/files/rOFBRGikFzPnwqx7L0Qx" alt="Left-to-right flowchart of the cbETH (Mainnet) price feed: rate and Chainlink inputs combine into a USD price, with a staleness gate."><figcaption><p>cbETH (Mainnet) price feed — how its oracle inputs compose into a USD price, with the staleness gate.</p></figcaption></figure>

***

## Price calculation

```
price = exchangeRate() (18) × (ETH/USD) (8) / 1e18      // USD, 8 dec
```

| Input          | Source                                              | Description                      |
| -------------- | --------------------------------------------------- | -------------------------------- |
| `exchangeRate` | `IcbETH.exchangeRate()` on cbETH (18 dec)           | ETH per 1 cbETH                  |
| ETH/USD        | NAV base — `getPriceDataNoDivergence(WETH)` (8 dec) | the NAV's primary WETH/USD price |

`exchangeRate()` is read directly from the cbETH contract and grows as staking rewards accrue. Output decimals are inherited from the ETH/USD feed (8).

***

## Constructor

```solidity
constructor(
    address cbEth_,
    address nav_,
    address baseAsset_
)
```

| Parameter    | Description                                                                                |
| ------------ | ------------------------------------------------------------------------------------------ |
| `cbEth_`     | cbETH token address (also the supported underlying)                                        |
| `nav_`       | NAVCalculator (proxy) — supplies the base asset's USD price via `getPriceDataNoDivergence` |
| `baseAsset_` | The registered base asset whose USD price is read (WETH)                                   |

***

## Staleness

`getLatestPrice()` returns stale if `exchangeRate()` returns `0`, or if the NAV reports the base asset (WETH) stale — all its feeds stale. The base leg's `updatedAt` comes from the NAV's selected WETH feed. The `exchangeRate()` call has no independent heartbeat.

***

## Chains

Deployed on **Ethereum**. For the Base deployment using a direct Chainlink cbETH/ETH feed, see [cbETH (L2)](/funds/infrastructure/onchain-accounting/price-feeds/cbeth-l2.md).


---

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