What Is Block Time?
Also known as: Block Interval, Block Generation Time
In short
Block time is the average time between the production of two consecutive blocks on a blockchain network. It is one of the key parameters affecting how quickly transactions are confirmed and the network's transaction capacity.
Each network's block time is set by the protocol. In Bitcoin, the target is about 10 minutes; as mining power changes, the difficulty is readjusted every 2,016 blocks so that the average stays close to this target. Because finding a block in Proof of Work is a probabilistic process, the time of individual blocks can vary from a few seconds to more than an hour. Ethereum, after moving to Proof of Stake, uses fixed 12-second time intervals (slots).
A short block time lets transactions receive their first confirmation sooner and improves user experience. However, if new blocks are produced before blocks have propagated through the network, multiple valid blocks can occur at the same time; this leads to temporary chain forks and, in Proof of Work networks, wasted mining power. For this reason, the choice of block time is a balance between speed, security and decentralization.
Block time and finality are not the same thing. In Bitcoin, even after a transaction is included in a block, the possibility of it being reversed is not completely eliminated; for this reason, for large amounts, six confirmations, or about one hour, are generally awaited. Crypto exchanges also require a different number of confirmations for each network before accepting deposits.
Last updated: · This content is for information purposes only and is not investment advice.