THE FINAL BLOCK

The year 2140 is etched into the foundational lore of Bitcoin. It represents a pre-programmed, unalterable endgame: the moment when the final fraction of a new bitcoin is issued into circulation. After 33 halvings, the block subsidy will mathematically reach zero. This event will mark a step into the unknown, commencing Bitcoin’s transition into the post-mining reward era.

Many experts have attempted to predict what will happen on that date – but its distance and the number of variables involved make such ventures highly speculative. This much appears to be broadly agreed though: if Bitcoin is still a going concern in 2140 – and is still secured by Proof of Work – the cessation of mining rewards will not induce security issues caused by miners powering down their rigs. After all, there’s more than a century in which to plan its succession in a world where all bitcoins that will ever exist have been issued.

One of the most fascinating things about Bitcoin’s most distantly knowable event is that it was one of the first characteristics to have been programmed into it. When the mining subsidy ceases in 2140, it will be a direct consequence of the code Satoshi Nakamoto wrote in 2008, some 132 years earlier.

Satoshi famously crafted Bitcoin to mimic the economics of mining a finite precious metal like gold, where initial discoveries are larger and subsequent extraction yields diminish over time, leading to increasing scarcity. To achieve this, he set the mining supply to reduce by half every 210,000 blocks – or approximately every four years.

In 2012, the first halving event saw the block reward cut to 25 BTC. In 2016, it halved again to 12.5. Then 6.25 in 2020 and down to 3.125 in 2024. In 2036, the reward will be 0.390625 BTC per block, and by 2136 will have diminished so greatly that the reward will be a nominal 0.00000001 BTC – leaving mining rewards to effectively reach zero four years later.

The Final Countdown

While Bitcoin’s final issuance date is sure to prompt endless speculation and anticipation in the decades to come, the security of the Bitcoin network in a post-reward world will have long since been determined. By the 2032 halving, over 98% of all bitcoins will have been mined. As a result, the final century of issuance will be dedicated to mining an increasingly infinitesimal fraction of the total supply, highlighting the diminishing role of the block subsidy long before it formally ends.

Depending on the value of Bitcoin as 2140 draws near, mining these final fractions of a coin may even become trophy challenges; tests of computing power rather than pursuits of profit. The equivalent to climbing a lofty mountain for nothing more than the challenge it presents. The very last block subsidy is expected at Bitcoin block #6,929,999, estimated to be mined around February 23, 2140, which will award the miner the final new fraction of a bitcoin – just 1 sat. Prior to that, it will take roughly 36 years for the last whole BTC to trickle out to miners.

Satoshi, always operating with one eye to the future, was fully aware that the block reward subsidy was a finite bootstrapping mechanism. In a 2010 forum post, he stated with remarkable foresight: “In a few decades when the reward gets too small, the transaction fee will become the main compensation for [mining] nodes.”

This single sentence confirms that the 2140 event and the subsequent reliance on a competitive fee market were planned from the beginning. Or as Satoshi memorably put it: “I'm sure that in 20 years there will either be very large transaction volume or no volume.” As it stands, the former prediction appears likelier, with the fees embedded in every Bitcoin block providing ample incentives for miners to keep doing their thing.

For as long as users are willing to pay a few satoshis in fees to send bitcoin, and for as long as Bitcoin holds immense value, there will be grounds for miners to continue finding new blocks. Of course, any number of black swan events could yet prevent Bitcoin from seeing the year 2140, from alien invasion to nuclear apocalypse. But as it stands, the protocol Satoshi created is on course to meet this milestone exactly as he planned it.

The current generation of Bitcoiners will never know how much Bitcoin is worth on that momentous date. But they know, with absolute certainty, what the block reward will be.