The number of blocks before a block, starting with the genesis block at height zero.
Block height meaning
Block height identifies a block's position in a particular chain. The genesis block has height 0, its child has height 1, and the count continues upward. Height is useful for discussing confirmations, activation points, and the subsidy schedule.
How it works in Bitcoin
A height is not globally unique during a temporary fork because two competing blocks can have the same height. A block hash identifies one exact block; height identifies a position.
A simple example
If the chain tip is height 900,005 and a transaction was included at height 900,000, people commonly describe it as having six confirmations: its own block plus five blocks after it.
Why Block height matters
Network terms explain how independently operated software shares, validates and orders information. They help separate a convenient data viewer from the rules a node actually enforces.
What people often get wrong
Do not confuse block height with a timestamp. Blocks arrive at irregular intervals, and header times are constrained but are not a precise clock.
Quick checks before using the term
- Which actor performs this job?
- Is the behavior a consensus rule or an implementation choice?
- What evidence can a node verify independently?
Apply these questions to the concrete example above. A precise answer is more useful than repeating the definition without naming the actor, rule or failure path.
Block height compared with Block
Block height: The number of blocks before a block, starting with the genesis block at height zero.
Block: A validated batch of transactions linked to the block before it.
The two ideas are related, but they answer different questions. Use the definitions above to name the actor, rule, or unit you actually mean instead of treating the terms as interchangeable.
Check the primary reference
This entry was reviewed 2026-08-04. The linked source is the place to confirm exact protocol or software behaviour when an implementation or documented rule changes.
Bitcoin Developer Guide: Block Chain ↗