Luck
The ratio of expected blocks to actual blocks found. Above 100% means lucky (found blocks faster), below 100% means unlucky.
What is Mining Luck?
Luck in mining is a statistical measure comparing how many blocks a pool was expected to find versus how many it actually found over a given period. It is expressed as a percentage where 100% means the pool found exactly the expected number of blocks.
How Luck is Calculated
The formula is straightforward:
Luck = (Expected Blocks / Actual Shares to Find Block) x 100%
Or equivalently for a period:
Luck = (Blocks Found / Expected Blocks) x 100%
- Above 100%: The pool found more blocks than expected -- lucky
- Exactly 100%: The pool found exactly the expected number -- average
- Below 100%: The pool found fewer blocks than expected -- unlucky
For example, if a pool's hashrate suggests it should find 10 blocks per day but it actually finds 12, its luck is 120%.
Short-Term Variance
Luck can vary dramatically over short periods. A pool might have 150% luck one day and 70% the next. This is normal and expected -- mining is a probabilistic process where each hash attempt has an independent, tiny probability of finding a block.
Smaller pools experience wider luck swings because they find fewer blocks in any given period. A pool finding 2 blocks per day might see luck range from 0% to 300% on individual days. A large pool finding 50 blocks per day will have luck much closer to 100% on most days.
Long-Term Convergence
Over extended periods, every pool's luck converges toward 100%. This is the law of large numbers in action. A pool's 30-day or 90-day luck should be very close to 100%, regardless of short-term fluctuations. If a pool consistently shows luck significantly below 100% over long periods, it may indicate problems (unreported blocks, incorrect hashrate reporting, or infrastructure issues).
Luck and Your Earnings
For PPLNS miners, luck directly affects payouts: lucky periods mean more frequent block discoveries and higher earnings. For FPPS miners, luck has no impact because the pool pays a fixed rate per share regardless of blocks found. This is one reason why FPPS pools charge higher fees -- they absorb the luck variance that would otherwise affect miners.