Share

A share is a proof of work submitted by a miner to a mining pool, demonstrating that the miner performed a certain amount of computational work. Shares are used by pools to measure each miner’s contribution and distribute rewards accordingly.

Understanding Shares

When mining in a pool, the network difficulty is typically far too high for any single miner to find a valid block in a reasonable time. Instead, the pool sets a much lower “share difficulty” so that miners can submit results frequently. Each valid submission at or below this lower difficulty is called a share.

Think of gold mining. Finding an entire gold nugget (a valid block) is extremely rare, but the mining company (pool) asks you to bring in any rock that contains traces of gold (a share). At the end of the day, the company pays everyone based on how many gold-bearing rocks they brought in.

Every share has a chance of also meeting the full network difficulty, in which case it represents a valid block. The pool operator checks every submitted share: if it meets the network target, the block is broadcast to the Bitcoin network, and the pool earns the block reward.

Tip

The share difficulty assigned by a pool is typically adjusted dynamically based on the miner’s hashrate. Faster miners receive a higher share difficulty so they submit shares at a manageable rate, while slower miners get a lower share difficulty to ensure they submit shares often enough to track their contribution accurately.

Practical Example

A pool sets share difficulty at 100,000 while the network difficulty is 80 trillion. A miner hashing at 100 TH/s might submit hundreds of shares per minute at this share difficulty. Each share proves the miner is working. When one of those shares happens to also beat the network difficulty, the pool finds a block and distributes the reward based on each miner’s accumulated shares.

See also

• Stale Share
• Mining Pool
• Difficulty
• PPS
• PPLNS