> ## Documentation Index
> Fetch the complete documentation index at: https://circle-devdocs-test-ai-codegen-component.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CCTP Block Confirmations

> Block confirmation requirements for attestations by chain

Before signing an attestation for a source chain event, Circle waits for a
specified number of onchain block confirmations to achieve
<Tooltip tip="The point at which a transaction is fully finalized on-chain and can no longer be reversed or reorganized. This ensures the highest level of security and certainty before attestation. Hard Finality requires the transaction to reach full consensus on the source blockchain, typically resulting in longer processing times.">hard finality</Tooltip>.

The tables below show the average time required for an attestation to become
available after fast and standard messages are emitted onchain, respectively.

<Note>
  **Note:** These values are subject to change.
</Note>

## CCTP V2 Fast Message Attestation Times

| Source Chain    | Number of Blocks | Average Time |
| --------------- | ---------------- | ------------ |
| **Ethereum**    | 2                | \~20 seconds |
| **Arbitrum**    | 1                | \~8 seconds  |
| **Base**        | 1                | \~8 seconds  |
| **Codex**       | 1                | \~8 seconds  |
| **Ink**         | 1                | \~8 seconds  |
| **Linea**       | 1                | \~8 seconds  |
| **OP Mainnet**  | 1                | \~8 seconds  |
| **Plume**       | 1                | \~8 seconds  |
| **Solana**      | 2-3\*            | \~8 seconds  |
| **Unichain**    | 1                | \~8 seconds  |
| **World Chain** | 1                | \~8 seconds  |

## CCTP V2 Standard Message Attestation Times

| Source Chain        | Number of Blocks  | Average Time         |
| ------------------- | ----------------- | -------------------- |
| **Ethereum**        | \~65\*            | \~13 to 19 minutes\* |
| **Arbitrum**        | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Avalanche**       | 1                 | \~8 seconds          |
| **Base**            | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **BNB Smart Chain** | 3                 | \~2 seconds          |
| **Codex**           | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **HyperEVM**        | 1                 | \~5 seconds          |
| **Ink**             | \~65 ETH blocks\* | \~30 minutes\*       |
| **Linea**           | 1                 | \~6 to 32 hours\*\*  |
| **OP Mainnet**      | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Plume**           | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Polygon PoS**     | \~2-3             | \~8 seconds          |
| **Sei**             | 1                 | \~5 seconds          |
| **Solana**          | 32                | \~25 seconds         |
| **Sonic**           | 1                 | \~8 seconds          |
| **Unichain**        | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **World Chain**     | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **XDC**             | 3                 | \~10 seconds         |

<Note>
  **Block confirmations for L2s to Ethereum**

  Layer 2 (L2) blockchains publish transaction data in batches to Ethereum L1,
  and the frequency of these posts varies by chain. Most OP Stack-based chains,
  including Codex, post state updates using EIP-4844 blob transactions
  approximately every \~15 minutes. After a batch is posted, Circle waits for the
  Ethereum L1 block containing the batch to finalize, which typically happens
  after \~65 blocks (13 to 19 minutes), before issuing an attestation.

  **Hard finality for Linea**

  The typical time before hard finality on Linea is 6-32 hours.

  **Finality for Solana**

  For Solana Standard Messages, Circle waits for block finality before
  attesting. This takes 32 blocks. For Fast Messages, Circle only waits for the
  block to be confirmed, meaning the block has received votes from validators
  representing over two-thirds of the total stake. This typically takes 2-3
  blocks.
</Note>