I'd like to ask if someone can help explain this definition found on https://en.bitcoin.it/wiki/Target

"The SHA-256 hash of a block's header must be lower than or equal to the current target for the block to be accepted by the network". I understand that target means difficulty. But I don't understand what the hash being lower than the target actually means.

I looked on youtube for explanations of target hash but they returned an investopedia definition.

Thank you in advance.

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    Does this answer your question? How often does target hash change and how to find it?. The hash is a number. Just like 33 is a number. The target is a number. Just like 76 is a number. We can see that a hash is less than a target just like we can see 33 is less than 76. if hash < target { publish_block() } else { nonce++; continue loop } Apr 14, 2022 at 9:49

2 Answers 2


Target and Difficulty are separate concepts. You may want to take a look at this answer I wrote for another question: How often does target hash change and how to find it?


There are no magic math to understand for this: simply it was needed some target to let people calculate and mine with some difficulty having success after a certain time. The “lower than” has been chosen, but “greater than” some number or “comprised between “ a couple of number works in the same way. The “lower than” has the useful property that declaring a single parameter (the threshold) you tune all the miner on the target (i.e. 0 < x < threshold) and that as lower is the parameter as higher is the number of guess you should test before to find a good one. You need to define some interval because it is practically impossible to find a single number which when passed trough sha256 yields a certain target number value exactly.

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