# block_height · Rell standard library · Chromia Docs (concept)

> val block_height: integer The height of the block being built, i.e. the number of completed blocks in the blockchain. For each block, the height is the num

Source: https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/op_context/block_height/

PROPERTY

# block\_height

```signature
val block_height: integer
```

The height of the block being built, i.e. the number of completed blocks in the blockchain.

For each block, the height is the number of blocks before it, therefore the first block in the chain
has height `0`, the second has height `1`, etc.

**Throws**

* `exception` — if there is no operation context

Since 0.9.0

[View this page on docs.chromia.com](https://docs.chromia.com/pages/rell-stdlib/-rell%20-system%20-library/op_context/block_height.html)Generated API reference, mirrored from the live docs