Finality

Intermediate

更新済 Sep 21, 2026

What Is Finality?

Finality is the assurance that a confirmed blockchain transaction cannot be altered, reversed, or canceled after it is completed.

Finality measures how long a user must wait for a reasonable guarantee that a transaction recorded on the blockchain will not be undone. The lower a network's latency, the faster it can reach finality.

How Long Does Finality Take?

Most blockchains offer probabilistic finality, meaning a transaction is not instantly final but becomes "more and more final" as additional blocks are confirmed on top of it.

On Bitcoin, which uses proof of work, a block is produced roughly every 10 minutes, and many services treat a transaction as settled after 6 confirmations, or about 60 minutes.

Ethereum, which uses proof of stake with the Casper FFG mechanism, reaches economic finality once a transaction is included in a checkpoint that validators finalize.

Source

This currently takes about two epochs, or roughly 13 minutes under normal network conditions.

Source: Vitalik’s Notes on Paths toward single-slot finality

A research goal called single-slot finality aims to shorten this to around one 12-second slot. However, as of 2026, it has not shipped to the Ethereum mainnet and remains under active development.

Types of Finality

The two broad categories are probabilistic and deterministic finality.

Probabilistic finality: used by proof of work networks like Bitcoin, it means confidence grows with each additional confirmation but never reaches an absolute guarantee.
Deterministic finality: used by many proof of stake networks, it means a transaction is final the moment a defined set of validators signs off on it, and the protocol rules make no provision for reversing it.

Why Finality Matters

Finality is an essential feature for businesses that accept cryptocurrency payments. Waiting a long time for a transaction to settle can be inconvenient and costly, so low latency helps make a payment system practical. Companies also need to know within a short time frame whether they truly control an asset.

It’s worth noting that finality can, in rare cases, be affected by a chain reorganization, where the network temporarily settles on a different version of recent history before converging again. This is one reason many platforms wait for several confirmations rather than acting on a single one, balancing speed against the small residual risk of reversal.

Finality also shapes how different networks are used. Chains with fast, deterministic finality are often preferred for applications that need quick certainty, such as trading venues that credit deposits before allowing withdrawals of a different asset, or cross-chain bridges that lock funds on one network and mint a representation on another. Networks with slower finality can still be used for these purposes, but the systems built on top must decide how much confirmation depth is enough before treating a transfer as settled.

Learn more: What Is Blockchain and How Does It Work?

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