# Constraining ruler tool to a perfectly horizontal or vertical line

**URL:** <https://discourse.slicer.org/t/constraining-ruler-tool-to-a-perfectly-horizontal-or-vertical-line/41229>\
**Category:** Support\
**Created:** [January 22, 2025, 7:17pm UTC](https://discourse.slicer.org/t/constraining-ruler-tool-to-a-perfectly-horizontal-or-vertical-line/41229 "2025-01-22T19:17:51Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Bella\_Salerno](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/bella_salerno/32/79193_2.png) [@Bella\_Salerno](https://discourse.slicer.org/u/Bella_Salerno)\
**Post date:** [January 22, 2025, 7:17pm UTC](https://discourse.slicer.org/t/constraining-ruler-tool-to-a-perfectly-horizontal-or-vertical-line/41229/1 "2025-01-22T19:17:51Z")

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Hello,

I have a question regarding the ruler tool and creating a measurement line. Is there a way to ‘snap’ the line to a perfectly horizontal or vertical line? For example, in other applications I can hold down the “shift” key and this constrains the line I’m drawing to a horizontal (0 degree) line.

Thanks!