Why Bitcoin Halving Calculators Are Out of Sync

The Bitcoin halving is scheduled to occur every 210,000 blocks, or roughly every four years. This particular event will be executed automatically by the network at exactly blockheight 840,000. Based on the way Bitcoin’s creator Satoshi Nakamoto designed the system, bitcoin miners “find” the next block to hash to the blockchain every 10 minutes, meaning it should be easy to figure out precisely when the next halving should happen down to the minute.