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 hard finality.

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

Note: These values are subject to change.

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

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.