What this chart shows
The historical portion of this chart is Bitcoin's actual circulating supply, fetched from Coin Metrics. The projected portion — everything after today — isn't a forecast in the usual sense: it's a direct calculation from the protocol's fixed rule that the block reward halves every 210,000 blocks, run forward assuming a constant 10-minute average block time.
This is the one page on this site where the future line isn't a statistical guess about human behavior — it's a computation about a rule written into the software every full node already enforces. The only real uncertainty is the exact calendar date each future halving lands on, which depends on actual network hash rate.
How to read it
The gauge shows what share of the eventual 21 million BTC cap has already been issued. Because issuance halves on a fixed schedule while circulating supply keeps compounding toward the cap, the curve flattens dramatically over time — the vast majority of all Bitcoin that will ever exist has already been mined, with the remainder trickling out over the next century-plus in ever-smaller amounts.
Limitations
The exact calendar date of each future halving is an estimate, not a certainty — identical to the caveat on this site's Halving Countdown page. This chart assumes a constant 10-minute average block time for every future epoch; sustained hash rate growth or decline over the coming decades would shift the actual dates.
This projection assumes Bitcoin's core issuance rule is never changed. That's the entire premise of the protocol's monetary policy holding, but it's a social and political assumption about future consensus, not a mathematical certainty — the rule has never been changed in Bitcoin's history, but "never changed yet" and "cannot be changed" are different claims.
The theoretical maximum is often rounded to 21 million, but due to how integer satoshi rounding compounds across every halving epoch, the true asymptotic cap is very slightly below that — a well-known technical footnote that doesn't change the shape of this chart in any way visible at this scale.