2140 consensus for 21M bitcoin?

[Hockeybum]

Can someone explain to me why the year 2140 is the consensus as to when the last bitcoin will be mined?  There are already 16,667,325 bitcoin in existence as of now.  There will be approximately 2M mined in the next 3 years, 1.3M mined in the following 4 years, 657k in the subsequent 4 years and 328k in the subsequent 4 years.  That will already be 20,937,825 by Jan 2033.  The remaining 62k will be mined by the end of 2035.  Can someone look over the numbers and tell me what I'm missing that my estimate is 100 years off from everything I've read?

[Frank0209]

Mining difficulty is increasing very quickly so it's the biggest reason why Bitcoin will be mined out until 2140 . It makes Bitcoin mining become harder and harder day by day so it's really hard to know the exaclty number of Bitcoin will be mined in next few years. Beside in the future there will be a lot of hardfork happened and maybe it's also the reason make the mining difficulty increasing quickly .

[Hockeybum]

I understand mining difficulty is increasing, however the mining protocol strives to set a block every 10 minutes which it adjusts from time to time to account for that difficulty.  So over time, even though difficulty increases, the network adjusts to make the calculations harder to compute the nonce which solves the equation, in order to maintain the 10 minute (on average) block. 

[DannyHamilton]

- snip -

That's a bunch of sig ad spam nonsense.  You clearly don't know what you are talking about and should refrain from answering any more questions here at bitcointalk until you have taken the time to actually understand how things work.  Otherwise, you are likely to spread misinformation and cause people confusion about how bitcoins works.

Can someone explain to me why the year 2140 is the consensus as to when the last bitcoin will be mined?  There are already 16,667,325 bitcoin in existence as of now.

I think we are around 16,668,787 right now, but your estimate is close.

There will be approximately 2M mined in the next 3 years,

We are currently at block height 493503.  That means we have 136497 more blocks at 12.5 bTC per block until then next block subsidy halving.
136497 * 12.5 = 1706212.5 BTC.

That's quite a bit less than 2 million.

1.3M mined in the following 4 years,

You are rounding off (which is probably where you are encountering your confusion), but otherwise you are correct

In the year 2020 (at block height 630000), the block subsidy will be cut in half from 12.5 BTC per block to 6.25 BTC per block for the next 210000 blocks.  It will take approximately 4 years to create those 210000 blocks.
210000 blocks X 6.25 BTC per block = 1312500 BTC

657k in the subsequent 4 years

There you go, rounding again...
210000 X 3.125 = 656250 BTC

and 328k in the subsequent 4 years.

And rounding again...
210000 X 1.5625 = 328125 BTC

That will already be 20,937,825 by Jan 2033.

Check your math...
16,668,787 + 1706212.5 + 1312500 + 656250 + 328125 = 20,671,874.5

The remaining 62k will be mined by the end of 2035.

Over the next 2 years after the block subsidy gets cut in half from 1.5625 BTC to 0.78125 BTC:

105000 X 0.78125 = 82031.25 BTC will be mined (not 62k).

20,671,874.5 + 82031.25 = 20,753,905.75 BTC

At that point there will still be 246,094.2269 more bitcoins to mine over the remaining 105 years or so.

[Hockeybum]

Thank you for the reply, yes, I did round numbers because I wasn't sure about block heights and exactly when the halving occurs.  So, ~99% of bitcoin will be mined by 2035 and the remaining ~1% will take 105 years to complete because of the ever decreasing block reward.  Thanks again for the detailed reply.

[DannyHamilton]

~99% of bitcoin will be mined by 2035 and the remaining ~1% will take 105 years

There you go with that rounding again...

 

20,753,905.75 / 20999999.9769 = 98.828122727...%  (yes, very close to 99%)

246,094.2269 / 20999999.9769 = 0.01171877272...% (yes, very close to 1%)

Note that we will never get to 21 million.  The proper phrases are things like:

• "There will never be more than 21 million bitcoins."
• "The total bitcoins ever created will be less than 21 million."
• "There is a limit of nearly 21 million bitcoins to be created."

Unfortunately, many people accidentally rephrase that to things like:

• "There will only be 21 million bitcoins."
• "After 21 million are created, there won't be any more."

While these generalizations are fine for general conversation, they tend to cause confusion when people try to understand the exact technical details.

The actual limit on the number of bitcoins that theoretically could have been created back when the software was first released in 2009 was 20,999,999.9769 BTC.

Due to a bug early on, a miner (or miners) failed to reward themselves the full block reward that they were entitled to.  This had the effect of reducing (by the amount that they failed to pay themselves) the total number of bitcoins that can ever be mined.  So the actual total will be a bit less than the theoretical maximum.

[quantumcomputing11]

Granted this is under the assumption that computing power stays the same or does this take into account Moores law? Btw even if it does take into account Moores law what about the next 100 years+ of innovation? Surely

somewhere in there we invent a quicker and better way to mine bitcoins. I am taking a wild guess at it but I think we will end mining bitcoin sometime before 2100 comes around I am not sure when that would be though.

[Hockeybum]

Quantum, the network corrects the difficulty to try to maintain a 10 minute average block time

Danny, Thank you so much for all the detail in your reply; sorry for the rounding.  I just created a spreadsheet and now see the errors that rounding can cause when dealing with halving and over 100 years of rewards.

[DannyHamilton]

Granted this is under the assumption that computing power stays the same or does this take into account Moores law? Btw even if it does take into account Moores law what about the next 100 years+ of innovation? Surely

somewhere in there we invent a quicker and better way to mine bitcoins. I am taking a wild guess at it but I think we will end mining bitcoin sometime before 2100 comes around I am not sure when that would be though.

Nonsense.  Absolute nonsense.  Please avoid answering any technical questions about bitcoin until you've taken the time to learn a little bit about how it works.  Otherwise you are just going to spread misinformation and cause more confusion.

Inventing a quicker way to mine bitcoins does NOT significantly speed up the release of new bitcoins.  It just increases the difficulty.

Every 2016 blocks (approximately every 2 weeks) EVERY node on the Bitcoin network re-calculates the difficulty target.

If it takes less than 20160 minutes to mine those 2016 blocks, then the blocks are happening too fast and the difficulty is adjusted proportionally to slow the block solving back down to 10 minutes average per block.

If it takes more than 20160 minutes to mine those 2016 blocks, then the blocks are happening too slow and the difficulty is adjusted proportionally to speed the block solving back up to 10 minutes average per block.

So, if you suddenly came up with a new technology (and implemented it immediately after a difficulty retarget) that increased everyone's ability to solve blocks so that they could solve them 4 times as fast...  The next 2016 blocks would be solved in 5040 minutes (approximately 3.5 days) instead of 2 weeks. Then the difficulty would automatically be increased to be 4 times as difficult, and blocks would go back to being solved once every 10 minutes again.  You would only shave, at most, 11 days off of the 100+ years estimate.