The bitcoin halving explained: what it is, why it happens and when the next one is

Bitcoin has no central bank deciding how much new money to create. Instead, its supply follows a schedule written into the software that every node runs. The most famous part of that schedule is the halving: the moment, roughly every four years, when the number of new bitcoins created per block is cut in half.

Halvings get a lot of attention because they’re one of the few predictable events in a very unpredictable market. This guide explains exactly what changes, and what doesn’t.

Where new bitcoins come from

New bitcoins are created through mining. Miners compete to add the next block of transactions to the blockchain. The miner who succeeds receives a block reward, which, as the Bitcoin developer documentation explains, is made of two parts:

1. The block subsidy: newly created bitcoins.
2. The transaction fees paid by the transactions in that block.

The halving only affects the first part.

The rule: half every 210,000 blocks

The schedule is defined in Bitcoin Core, the reference software. The function that calculates the subsidy starts at 50 bitcoins per block and divides it by two after every 210,000 blocks. The code comment says it plainly: the subsidy is cut in half every 210,000 blocks, which will occur approximately every 4 years.

Why four years? According to Bitcoin.org, new blocks are added approximately every 10 minutes on average, although block discovery is probabilistic. 210,000 blocks × 10 minutes is about 4 years.

The halvings so far

Block height	Subsidy per block after it	Date (block timestamp, UTC)
0 (launch)	50 BTC	January 2009
210,000	25 BTC	November 2012
420,000	12.5 BTC	July 2016
630,000	6.25 BTC	May 2020
840,000	3.125 BTC	April 2024
1,050,000 (next)	1.5625 BTC	Expected around 2028

The date of the next halving can’t be predicted to the day, because it depends on when block 1,050,000 is mined, and block times vary. Block explorers estimate it from the current block height and recent block times.

The 21 million cap

Because the subsidy halves again and again, the total number of bitcoins that will ever be created converges to a limit. Bitcoin.org states that only 21 million bitcoins will ever be created. Strictly, the total ends up very slightly below 21 million, because the subsidy is rounded down to the smallest unit (the satoshi, one hundred-millionth of a bitcoin) at each step.

The subsidy keeps halving until it rounds down to zero, more than a hundred years from now. After that, miners will be paid only through transaction fees.

What a halving changes, and what it doesn’t

What changes:

• The flow of new supply. After the April 2024 halving, about 450 new bitcoins are created per day instead of about 900 (144 blocks a day × 3.125 BTC, versus × 6.25 BTC).
• Miner revenue. Overnight, miners earn half as many new bitcoins per block. Unless the price of bitcoin or transaction fees rise enough to compensate, less efficient miners may become unprofitable.

What doesn’t change:

• Your bitcoin. Halvings don’t affect the coins you already hold, or how you send and receive them.
• Transaction rules. Nothing about how transactions work changes at a halving.
• Certainty about the price. Halvings are often linked with past price rallies, but a handful of past events is not a reliable pattern, and halvings are widely anticipated by the market. Many other factors move bitcoin’s price.

Should you buy before a halving?

This guide doesn’t give investment advice. What official sources consistently stress is the risk: the CFTC notes that crypto values are driven purely by supply and demand and are more volatile than traditional currencies. A predictable cut in new supply is one input among many, not a reason on its own to invest money you can’t afford to lose.

If you do invest, a disciplined approach such as dollar-cost averaging avoids betting everything on one date. And a registered platform matters more than timing: see how to choose a crypto exchange.

Summary

• The block subsidy started at 50 BTC and halves every 210,000 blocks, about every four years.
• Since April 2024 it’s 3.125 BTC per block; the next halving, at block 1,050,000, should bring it to 1.5625 BTC, around 2028.
• Total supply converges to just under 21 million BTC.
• Halvings slow new supply and squeeze miners; they don’t guarantee anything about the price.