I just ran into the idea of immature coins. Can someone explain to me the idea behind immature coins and what was the purpose of it?

1 Answer 1


Immature coins are coins that were created in a block reward and haven't aged sufficiently, yet. The problem with block rewards is that they could still disappear again, if the generating block ends up being invalidated by a competing block chain.

In order to minimize the confusion and subsequent problems from someone spending coins that end up disappearing later again, block rewards are considered immature until another 100 blocks descend from the generating block. After this approximately 16 hours and 40 minutes, the coins are mature and considered safe to be spent.

On the other hand, regular transactions that were confirmed in a block that got invalidated by a longer competing chain would just be picked up by another block. The difference here is that a regular transaction is based on prior knowledge of the coins, even if it is through a chain of transactions, while newly created coins would not be there to fund a transaction.

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    It may be worth adding that this is different from normal transactions, which (in the case there is no malicious intent) can just move to the new chain in case of a reorganization. This means the concept of maturity and confirmations are very different (the first is a protocol rule, the second a client-side policy). Feb 7, 2014 at 20:32
  • Thanks, good suggestion. I wrote a bit, but I will have to look tomorrow again, it's late and it might not be clear. ;)
    – Murch
    Feb 8, 2014 at 1:41

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