Bitcoin Mining Pool Concentration
How much of Bitcoin's block production each mining pool assembles, attributed by coinbase tag over a rolling one-week and one-year window.
Method
Blocks are attributed to pools by the tag written into the coinbase transaction, as reported by the mempool.space mining pools endpoint. Two windows are pulled on the same day: a rolling seven days and a rolling 365 days.
Each pool's share is its block count divided by the total blocks in the window. The Herfindahl-Hirschman index is the sum of squared percentage shares across all pools that found a block in the window.
The measurement is about authorship of blocks, not ownership of hardware. The pool assembles the candidate block, deciding which transactions go in, in what order, and which do not go in at all.
What this does not show
It does not show common ownership. A coinbase tag says nothing about who ultimately controls two separately branded pools, who supplies their hardware, or who they share infrastructure with. If any two names answer to the same parent, every figure here understates the position, and this dataset cannot detect that.
Attribution is a convention rather than a proof. Blocks carrying no recognisable tag land in an unknown bucket. One week is roughly a thousand samples, so the smaller entries carry real sampling error: a pool credited with four blocks could plausibly have found two or eight. The top three are far outside that noise; the bottom of the table is not.
It does not measure whether the concentration has ever been used. Building a block and censoring a transaction are different acts, and the register of who built what contains no evidence about the second.
Runs
| Run date | Top three pools, share of one-week blocks | Change | Files | Write-up |
|---|---|---|---|---|
| 4 August 2026 | 60.75% of the week's blocks built by three pools | First run | CSV · JSON | Read |
Next scheduled run
3 November 2026. Quarterly, against the same endpoint and the same basis. Each run is published at its own dated URL and nothing is ever overwritten, so this page accumulates runs while every past run stays exactly where it was cited.
Data files on this page are published under CC BY 4.0. Reuse them commercially or otherwise, with attribution to CoinageReport. The limitations statement travels inside the JSON envelope, and we would rather it was not stripped.