---
tag: 0EA4XFB0EY
kind: concept
name: Ceiling function
msc: [26A09]
sources:
  - url: https://en.wikipedia.org/wiki/Floor_and_ceiling_functions
    locator: lead section
---

## Summary

The ceiling function sends a real number $x$ to the least integer that is greater than or equal to $x$. We write $\lceil x \rceil$ for it.
For example, $\lceil 2.3 \rceil = 3$ and $\lceil -2.3 \rceil = -2$.