About block 903,168
Bitcoin block 903,168 was mined by Luxor on June 29, 2025 at 5:23 AM UTC, 27 min 2 s after block 903,167. That is slower than the 10-minute target; long gaps are normal, since every hash attempt is an independent draw with the same tiny chance.
It confirmed 3,048 transactions in 1.89 MB (99.8% of the 4 million weight-unit limit). The median transaction paid 2.00 sat/vB, up from 2.00 sat/vB in the block before, and all fees added up to 0.0404 BTC. With the 3.125 BTC subsidy of halving era 5, Luxor earned 3.1654 BTC for this block.
Block 903,168 is number 1 of 2,016 in difficulty epoch 448; 2,015 blocks remain until the next difficulty adjustment at block 905,183. The next halving is at block 1,050,000, 146,832 blocks after this one.
Its hash starts with 19 zeros: that is the proof of work, a number below the target that the whole network’s hashrate had to search for. Luxor found 43 blocks in the week before. Today the block has 72,436 confirmations, so it is settled beyond any practical doubt.
Why block 903,168 is notable
Block 903,168 opens difficulty epoch 448. Every 2,016 blocks, each node recalculates the mining difficulty from how long the previous epoch took: if those blocks arrived in less than two weeks, difficulty goes up; if they took longer, it goes down, never by more than a factor of four. The new value, 116,958,512,019,762, took effect with this block, found by Luxor on June 29, 2025 at 5:23 AM UTC, and applies until block 905,183; the following adjustment is at block 905,184.
Nobody schedules a retarget. It happens when the chain reaches the height, so the adjustment at block 903,168 came the moment Luxor found it, not on a fixed date. The rule keeps the average close to one block every ten minutes however much hashrate joins or leaves the network.
Of the 3.16538124 BTC that Luxor collected for this block, 3.125 BTC was new subsidy and 0.04038124 BTC came from fees, 1.3% of the total; leaving out the coinbase, its 3,047 transactions paid about 1,325 sats each on average.
Current difficulty epoch and next adjustment →
What’s inside a Bitcoin block
Every block, 903,168 included, is made of the same parts:
- Header
- Eighty bytes that miners hash over and over: the version, the hash of the previous block, the Merkle root that summarises every transaction, a timestamp, the difficulty target in compact form and a nonce. A block is valid when the hash of its header falls below the target.
- Coinbase transaction
- The first transaction, written by the miner. It spends no inputs: it creates the subsidy and collects the fees, and since BIP 34 it must also record the block height.
- Transactions
- Everything else in the block: payments taken from the mempool, usually picked by fee rate because space is capped at 4 million weight units. Block 903,168 holds 3,048, counting the coinbase.
- Fees
- The difference between what each transaction spends and what it creates. The miner claims them in the coinbase; they are the part of the reward set by demand rather than by the protocol.
- Subsidy
- New bitcoin created by the block, fixed by the halving schedule: 50 BTC at the start, halved every 210,000 blocks. At height 903,168 it is 3.125 BTC.