---
title: Units in FreeSewing
order: 40
---

FreeSewing uses _millimeter (mm)_ for all its internal units.
We do support both imperial and metrics units, which are displayed
as _cm_ or _inch_, but under the hood everything is handled in millimeter.

So as a pattern designer, you will work with mm.
When you write `1`, that’s one millimeter. When you write `7.8`, that’s 7.8 mm.

While you can use cm or inch on the FreeSewing website, that is merely a layer of
abstraction on top of the internal units, which are always mm.