Bitcoin Mining Pools: How They Work and Who Mines

A Bitcoin mining pool is a service that combines the hashrate of many independent miners and shares the block rewards among them according to the work each one contributes. Pools turn a rare, lottery-like reward into a steadier and more predictable income for their members.

Why pools exist

A single modern mining machine controls a vanishingly small fraction of the network's hashrate. Mining alone, it could wait many years — possibly forever — to find a block, even though its expected earnings over a very long period would be about the same. Few businesses can live with that much variance. By pooling hashrate, members find blocks frequently as a group and receive small, regular payouts instead of a rare jackpot.

The trade-off is a pool fee, typically a few percent, plus a degree of trust in the operator. The alternative, mining on your own, is covered in our guide to solo mining.

How a pool works

1. The pool builds a block template, choosing transactions from its mempool, and sends work to its miners, usually over the Stratum protocol.
2. Miners hash that template. Any result that meets an easier, pool-specific target counts as a share: proof that the miner is doing real work.
3. Occasionally a share also meets the network's real target. That is a valid block, and the pool broadcasts it.
4. The reward is paid to the pool's address, and the pool pays its members based on the shares they submitted.

Common payout schemes include PPS (pay per share: a fixed payment for every share, with the pool absorbing the luck), FPPS (similar, but also passing on an estimate of transaction fees) and PPLNS (pay per last N shares: members are paid only when the pool actually finds blocks, so they carry more of the variance).

A newer protocol, Stratum V2, encrypts the connection and can let individual miners choose the transactions in the blocks they work on, rather than leaving that decision entirely to the pool operator.

How we know which pool mined a block

Blocks have no official "author" field. Explorers identify pools from clues in the coinbase transaction: a text tag that many pools insert, often their name, and the payout addresses they use. These signals are reliable for well-known pools but not perfect, and a block with no recognisable marker is usually labelled "Unknown". FreeBTC's pools page shows who mined recent blocks and each pool's share of them.

Pool concentration and luck

A small number of pools find most blocks. In recent years Foundry USA and AntPool have generally been the two largest, followed by pools such as ViaBTC, F2Pool, SpiderPool, MARA Pool and Binance Pool, although the rankings shift from month to month. Shares are estimated by counting blocks over a period, so short windows are noisy: a pool with 10% of the hashrate can easily find 5% or 20% of the blocks on a given day.

Concentration is a frequent subject of debate. Pools decide which transactions go into their templates, so a few large operators have real influence over block contents. On the other hand, the hashrate belongs to the individual miners, who can switch pools within minutes if an operator misbehaves, and efforts like Stratum V2 aim to hand template construction back to them.

Frequently asked questions

Is a bigger pool better for a miner?

Not in terms of expected earnings. A large pool finds blocks more often but splits each reward among more hashrate. What really differs between pools is variance, fees and the payout scheme.

Can a pool steal or censor transactions?

A pool cannot spend anyone else's coins, because it cannot forge signatures. It can choose to leave certain transactions out of its own blocks, but any other pool can still include them.

Predicting which pool mines the next block is the first call in every FreeBTC round. Pool shares give you a baseline probability, but short-term luck is large — which is exactly what makes it a game. Check the current pool distribution and make your pick.