What are stale shares in Bitcoin mining?

01Read the pool’s share labels

A share is proof of work submitted to the pool. An accepted share passes the pool’s checks for an active job. A pool may also reject work below the assigned difficulty or reject a duplicate submission. Check your pool’s definitions to see whether stale shares have a separate counter or appear under rejected, and how the pool treats them for credit.

02Compare one worker over the same period

Write down the worker name, pool endpoint and time window, including the time zone. If the miner shows totals since startup, take the difference between two readings from the same session. A restart can reset those counters. Keep counts from the same screen together and check whether the pool reports counts or difficulty-weighted work.

• Example: 980 accepted, 15 stale and 5 other rejected submissions during the same hour, with each submission counted once.
• Stale share rate by count: 15 ÷ (980 + 15 + 5) = 1.5%.
• If the screen instead shows 980 accepted and 20 rejected including 15 stale, the total is still 1,000 submitted shares. Count the 15 only once.
• Use submitted shares for this calculation. Leave out any work your firmware discarded before submission. A percentage by count can differ from the pool’s percentage by work because shares can have different difficulty.

03Find out where the spike occurred

Check the worker’s reconnects and pool messages around the first increase. Compare with another worker on the same route and time window. One affected worker gives you a reason to check its connection and recent configuration changes. Several workers spiking together give you a reason to ask about the shared network route or pool endpoint. The counters alone cannot identify the cause.

• Compare local and pool hashrate over the same hours

04Send the host the evidence it can use

For a hosted miner, share the time window, worker identifier, pool region, share counts and any reconnect timestamps with the operator. Ask whether the displayed worker belongs to one miner or represents routed fleet work. For a purchase, check the provider’s measured delivery and hosting tariff on the offer you plan to buy.

• Compare provider delivery records