4 min read · Updated 2026-10-25
SHA-256 in Bitcoin mining
SHA-256 is a cryptographic hash function: it turns any input into a fixed 256-bit fingerprint. Bitcoin mining is the repeated computation of SHA-256 hashes until one falls below a target.
What a hash does
The same input always gives the same output, but a tiny change in the input gives a completely different output. It is practical to compute a hash and practically impossible to work backwards from it.
How miners use it
A miner hashes the block header with a changing number, the nonce. The goal is a hash below the network target. There is no shortcut, so the only strategy is to try more hashes per second.
Why it needs special chips
Because the task never changes, chips built only for SHA-256, called ASICs, are far more efficient than general-purpose processors or graphics cards.
Frequently asked questions
Is SHA-256 broken?
No practical attack on SHA-256 is known.
Do other coins use it?
Some do, but they have their own networks and difficulty.
Try it yourself
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