Understanding the Last Bitcoin Mining Timeline

I’m kinda new here and folks suggested I dive deeper into Bitcoin before posting. I did some homework but I’m pretty lost, so figured I’d start this thread.

So, I got this: there are only 21 million BTC that can be mined. By 2021, around 18 million were already dug up. But it seems like the last BTC won’t be mined for like 120 years? How does this math actually work out?

It’s all about the block rewards and those halving events. Initially, miners got 50 BTC for a block. After 210,000 blocks, that reward dropped to 25, then to 12.5, and now it's 6.25. This halving keeps going until we hit the cap.

To sum it up: every 210,000 blocks, the reward halves until it reaches zero. When that happens, we won't have more than 21 million BTC out there.

This concept is kinda like Zeno’s paradox. Each halving cuts the reward in half, so the first 210k blocks gave us 10.5 million BTC, second set gave 5.25 million, and so on. Eventually, we end up with just under 21 million.

Exactly, right? The halving happens every 4 years, and mining gets tougher every time. This keeps BTC supply growth at a steady pace and that’s why folks think its value will rise. It’s smart to stock up during bear markets.

If you want a deeper dive, check out fillippone’s post about Equivalent Network Time. It’s got some solid breakdowns.

Thanks to @Darkdays, @BrewMaster, @BlackHatCoiner, @odolvlobo, and @Charles-Tim. I’m starting to wrap my head around this now. But I’m confused about something in Charles-Tim’s table. After 2108, it shows no BTC left to mine, but the supply continues to 2136. What gives?

The columns marked "Left To Mine" and "Mined BTC" skip the small fractions of a bitcoin. That "Reward" info is in satoshis, not whole BTC.

Right, so those total amounts might be created, but they won’t necessarily exist. Some BTC is lost forever or can’t be spent, so even if they’re counted, they aren't usable.

Thanks for that clarification, @DannyHamilton and @odolvlobo, feeling less confused now.

The actual coding part is what really matters. By the 64th halving, which is like 256 years from now, the base reward hits zero. But we’ll probably see it reach zero earlier since the rewards drop below 1 satoshi way before that.

But that code only helps people who can read it! If someone is asking about the math behind the BTC supply, they probably want a simpler explanation. Also, you missed the fact that 50 BTC equals this huge number in satoshis.

Yeah, that’s just a bit shift. I tried posting a simple PHP snippet but got blocked. The FAQ explains it simply, without getting bogged down in code.