What is block height?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 3 min
In short
Block height is simply the position of a block counted from the very first one. The genesis block is height 0, and every new block adds one. Confirmation counts and scheduled rule changes such as the halving are defined by this number, not by the clock.
Key points
- A sequential index with the genesis block at 0
- Increases by one with each new block
- Confirmations equal current height minus the block's height, plus one
- Protocol changes are often scheduled by height
Definition
An integer giving a block's position counted from the genesis block. It is used to refer to a point in the chain unambiguously.
A blockchain is a chain of blocks appended one after another. The genesis block sits at height 0, the next at 1, and so on. Look up any transaction in a block explorer and it will show you the height of the block that contains it.
Confirmations are just a subtraction. If your transaction landed in block 800,000 and the tip is now 800,006, it has seven confirmations. An exchange that credits deposits 'after 6 confirmations' is waiting for six more blocks to stack on top.
Rule changes are scheduled by height too. Bitcoin's halving occurs every 210,000 blocks — triggered by height, not by a date. Since block intervals vary, any published halving date is an estimate and the real moment drifts by days.
Watch out for
- · Two competing blocks can briefly share the same height, and one of them will later be discarded
- · At low confirmation counts the height can roll back, so do not treat a deposit as final