Confirmation Time

Confirmation time is a property of a blockchain, referring to the time it takes block producers on a blockchain network to process one block worth of transactions. Most blockchains will have a target confirmation time written into the codebase. For example, Bitcoin’s target confirmation time is ten minutes, which means on average, miners should produce a block of transactions every ten minutes.

In practice, usage of the term confirmation time can confuse this feature of the underlying network with a feature of services built on top of a network: how quickly funds may be accessed or transferred by users. While such operations’ confirmation time is partially a function of how quickly blocks are produced, it is also based on assumptions concerning when the operation may be considered reasonably secure. Because blocks are not absolutely confirmed in the sense of being permanently included on a blockchain, but rather, confirmed in the sense that there is a reasonably high probability that a block will not be orphaned, confirmation time with respect to services will depend more strongly on prevailing conventions. For example, the Bitcoin community currently counts blocks six deep as having a high probability of being permanently included on the chain, so reasonably secure.

For such reasons, wallets, exchanges, and payment processors wait a certain number of transactions before considering an observed transaction final and giving the user the ability to spend the funds. Such a service might require thirty full confirmations to be built on top of the block containing the transaction before giving users the ability to spend or transfer. In this case, a ten minute confirmation time for a blockchain will not translate to a ten minute period before a payment is considered processed.