Block reward

The block reward is what a miner can claim for mining a block. It has two parts: the block subsidy, which is new bitcoin created by the protocol, and the transaction fees from the block. The miner claims both in its coinbase transaction.

The subsidy has been 3.125 BTC since block 840,000 in April 2024. It halves every 210,000 blocks. The next halving is at block 1,050,000, which is about 75,000 blocks away from the tip at the time of writing. At the average pace of one block every 10 minutes, that is around April 2028. The halving page on our site tracks the countdown.

Why does the block reward exist?

The reward does two jobs. It pays miners for the work of hashing, which keeps them mining and the chain growing. It also puts new bitcoin into circulation, because no central bank issues coins. New coins enter only through mining, at a rate the protocol sets.

The reward also makes attacks costly. A miner who could rewrite recent blocks would need most of the network's mining power. It would usually earn more by following the rules and claiming rewards than by reversing its own payments. The reward does not make a 51% attack impossible, but it makes one a poor bet.

What is the block reward made of?

The block reward is the sum of two sources.

• The subsidy. A fixed amount of new bitcoin, set by the block's height. It is the only way new coins enter circulation.
• The fees. Every transaction pays a fee, which is the difference between what its inputs hold and what its outputs pay out. A miner can add all those fees to its claim.

A miner fills its block with the transactions that pay the most fees, since those fees are its share of the reward. A high fee makes a transaction more attractive to include. See fee for how the fee is set.

How is the subsidy calculated?

The subsidy depends only on the block's height. It starts at 50 BTC, which is 5,000,000,000 satoshis, and every 210,000 blocks it is halved. Halving a binary number is a right shift, so the rule can be written as one line:

def block_subsidy(height: int) -> int:
    """The subsidy in satoshis for a block at this height."""
    halvings = height // 210_000
    if halvings >= 64:            # shifting past 63 bits leaves nothing
        return 0
    return 50 * 100_000_000 >> halvings

print(block_subsidy(300_000))     # 2500000000 satoshis, which is 25 BTC
print(block_subsidy(840_000))     # 312500000 satoshis, which is 3.125 BTC

Bitcoin Core does the same calculation in its GetBlockSubsidy function in validation.cpp. A right shift rounds down. Once the subsidy is an odd number of satoshis, the next halving drops the odd satoshi. That rounding is why the total supply comes out a little under 21 million.

What is the halving schedule?

The subsidy halves at each multiple of 210,000 blocks. Here are the first halvings and the one coming next.

Era	Starts at block	Subsidy per block	Issued before this era
0	0	50 BTC	0 BTC
1	210,000	25 BTC	10,500,000 BTC
2	420,000	12.5 BTC	15,750,000 BTC
3	630,000	6.25 BTC	18,375,000 BTC
4 (current)	840,000	3.125 BTC	19,687,500 BTC
5 (next)	1,050,000	1.5625 BTC	20,343,750 BTC

Each era halves the one before it. The subsidy is down to a single satoshi in era 32, and it becomes zero at block 6,930,000, which at the average pace falls around the year 2140. The "issued before this era" column adds up every earlier era in full, so it shows how much of the supply was mined before each halving.

Why is the supply just under 21 million?

If every era were a clean number of satoshis, the total would be exactly 21 million bitcoin. It is not. Adding up the subsidies from the schedule gives 2,099,999,997,690,000 satoshis, which is 20,999,999.9769 BTC. The shortfall is 2,310,000 satoshis, or 0.0231 BTC. Each time an odd satoshi is halved, the rounding loses it, and the losses add up.

So the cap is a little under 21 million. People often call it "21 million" as shorthand.

When is the reward paid?

The coinbase transaction pays the reward into the chain, and its outputs can be spent only once the block is 100 blocks deep. See the coinbase transaction page for why.

Are fees going to replace the subsidy?

Eventually, yes. When the subsidy reaches zero, the block reward is made up only of fees. Until then, fees are a larger share of the reward at times of high demand. Fee income rises and falls with demand, while the subsidy is fixed. So miners will depend more on demand for block space as the subsidy shrinks.

What do two real blocks show?

Two blocks illustrate the split between subsidy and fees.

• Block 538,403 has a subsidy of 12.5 BTC and fees of 6,517 satoshis, so its reward is 1,250,006,517 satoshis.
• Block 400,021 has a subsidy of 25 BTC and fees of 1,166,059 satoshis, so its reward is 25.01166059 BTC.

In both blocks the miner's claim equals the subsidy plus the fees, so no coins were lost. You can check any block on our explorer at block 400,021 or block 538,403.

Can a miner claim less than the full reward?

Yes. A miner is free to claim less, and any amount it leaves unclaimed is lost, because no output holds it. Nothing forces a miner to claim everything. A claim of more than the reward, however, makes the block invalid.

The target page covers the last piece: the number a hash must beat.