Block luck
A sat's luck is its block's: how many more leading zero bits the block's hash has than its difficulty target required.
How luck is measured
A block is valid when its hash, read as a number, is at or below the target its header's bits encode. Write both as 256-bit numbers: the target starts with some number of zero bits, and the hash with at least as many. A block's luck is the hash's leading zero bits less the target's. A hash that only just met its target has luck 0, and each step up is about half as common as the one below it.
Every sat mined in a block shares that block's luck, and it never changes once the block is buried. About one block in eight hundred has luck 10 or more.
Why collectors care
Luck is not a rarity tier and has no category of its own: any sat has one, from an uncommon to a palindrome. It is a second, independent way to pick out sats within a category, such as uncommons from the luckiest blocks.
On this site
- The sat, UTXO and transaction pages show each sat's luck, and the listings grid has a Luck column you can sort by.
- Listings and sales can be filtered by Luck ≥ a minimum (and, through the API, a range such as
luck=8-12); an item passes when one of its sats does. - The Statistics can narrow every category's supply to the sats mined in blocks of a given luck. Holders count each address once, however many lucks it holds; luck does not combine with a year filter there.