You can calculate the number of #Bitcoin halvings that have occurred by dividing the current block height by the halving interval (210,000).

For example, if the current block height is 846735 / 210,000 = 4.03 halvings.

Where the block height of a block is the number of blocks preceding it in the blockchain.

The 210,000 constant is the number of blocks between two halvings.

A new block is mined approximately every 10 minutes.