---
title: math.SQRT1_2
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/variables/math-constants-limits/math-sqrt1-2
---

**Type:** FLOAT  
**Access:** read-only, constant

**Available in:** all subroutines

The value of the reciprocal of the square root of two (1/sqrt(2)).