# CCTP Block Confirmations V1

This is CCTP V1 (Legacy) version. For the latest version, see [CCTP](https://developers.circle.com/cctp).

Before signing an attestation for a source chain event, Circle waits for a specified number of onchain block confirmations to achieve hard finality. The table below shows the average time required for an attestation to become available after a message is emitted onchain.

{% hint style="warning" %}
Note: These values are subject to change.
{% endhint %}

### CCTP V1 Attestation Times

| Source Chain    | Number of Blocks  | Average Time         |
| --------------- | ----------------- | -------------------- |
| **Ethereum**    | \~65\*            | \~13 to 19 minutes\* |
| **Avalanche**   | 1                 | \~8 seconds          |
| **OP Mainnet**  | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Arbitrum**    | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Noble**       | 1                 | \~20 seconds         |
| **Base**        | \~65 ETH blocks\* | \~13 to 19 minutes\* |
| **Polygon PoS** | \~33              | \~75 to 120 seconds  |
| **Solana**      | 32                | \~25 seconds         |
| **Sui**         | 1                 | \~8 seconds          |
| **Aptos**       | 1                 | \~8 seconds          |
| **Unichain**    | \~65 ETH blocks\* | \~13 to 19 minutes\* |

{% hint style="info" %}
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. Some submit batches every few minutes, while others are less frequent. After a batch is posted, Circle waits for the Ethereum L1 block containing the batch to finalize, which typically happens after \~65 blocks, or 13 to 19 minutes, before issuing an attestation.
{% endhint %}

Previous: [CCTP Aptos Packages and Interfaces V1](broken://pages/4880ed1f887793fc790c8f85cd241cc7888f01fa)\
Next: [CCTP Chain Domains V1](/chainaiswap-docs/cross-chain-transfer-protocol/cross-chain-transfer-protocol-v1/cctp-chain-domains-v1.md)


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