Pool Luck

Pool luck is a metric that compares how many shares a pool was statistically expected to submit before finding a block against how many it actually took. It is usually shown as a percentage: the expected share count divided by the actual share count, times one hundred. A value above 100% means the pool found the block faster than probability predicted (lucky); below 100% means it took longer (unlucky). Luck is not a judgment on the pool's competence — it is a direct readout of the randomness at the heart of proof-of-work.

A worked example

Suppose a pool, given its share difficulty and the network target, was expected to need about 600,000 shares to find a block but actually found one after 300,000 shares. Its luck for that block is 600,000 / 300,000 = 200%. If the next block takes 1,200,000 shares, luck for that round is 50%. Over a single block, luck swings wildly; across many blocks it averages toward 100% because block discovery is a memoryless random process driven by raw hash attempts — every hash is an independent lottery ticket, and the network keeps no memory of how long the current round has run.

The math behind the swings

Block discovery follows Poisson statistics, and the waiting time for the next block is exponentially distributed. That distribution has a counterintuitive shape: the chance that a round runs longer than its expected duration is 1/e, roughly 36.8% — more than a third of all rounds are "unlucky" by definition. About 13.5% of rounds run past double the expected time, and roughly 5% past triple. The flip side is that many rounds resolve quickly, which is why short-term luck figures of 300% or 30% are unremarkable. The memoryless property also kills a common intuition: a pool that has gone twice its expected time without a block is not "due" — its odds on the next hash are identical to the moment the round began. Only the long-run average is predictable, and it converges on 100% for any honest pool.

Why it matters to your payouts

Luck directly affects payout timing in reward schemes that distribute only when the pool actually finds blocks — proportional and PPLNS-style systems. Under those models, an unlucky stretch means thinner payouts even though your hashrate never changed; fixed-rate PPS-style schemes instead absorb that swing on the operator's side, which is part of what the higher pool fee pays for. Understanding luck keeps operators from misreading short-term randomness as a broken miner or a bad pool: if your machines are submitting shares at their normal rate, your side of the system is healthy no matter what the luck chart shows. A pool whose luck sits persistently and significantly below 100% over hundreds of blocks is a different story — that pattern can indicate misreported statistics — but the sample size needed to draw that conclusion is far larger than most people assume. For a home miner or a solo miner, luck is the whole game condensed into one number.

Luck versus the numbers you control

The healthiest way to use a luck statistic is as a filter: it tells you which movements in your income to ignore. Your electricity rate, your machines' efficiency and uptime, your pool's fee and payout scheme — those are levers. Luck is weather. A dashboard that separates the two keeps you from re-tuning healthy machines after an unlucky week or crediting a lucky month to a tweak that did nothing. Solo miners live at the extreme end of this: their entire reward history is a luck chart, which is why solo dashboards lean on odds framing ("a block every N years at current difficulty") rather than luck percentages that would swing between zero and astronomical.

Pool luck is simply mining variance measured at the pool level, and the share counts it depends on are governed by each worker's share difficulty.

See live pool data in the pool centralization tracker.