CCTP Block Confirmations V1

Block confirmation requirements for attestations by chain

This is CCTP V1 (Legacy) version. For the latest version, see 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.

Note: These values are subject to change.

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*

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.