---
title: Millimeter options
---
:::warning
While FreeSewing supports millimeter options, we recommend
using [percentage options][1] and will not accept
contributions that use millimeter options.
:::
## Structure
A millimeter option should be a plain object with these properties:
- `mm` : The default value in millimeters
- `min` : The minimum that's allowed
- `max` : The maximum that's allowed
## Example
```js
options: {
elasticWidth: {
mm: 35,
min: 5,
max: 80
}
}
```
:::note COMMENT (by joost)
##### What's wrong with millimeter options?
Millimeter options do not scale.
Parametric design is the _raison d'être_ of FreeSewing and that core belief
that things should seamlessly adapt goes out the window when you use a `mm`
option because now you have a value that will not change based on the
input measurements.
You could argue that it's fine because _you can just lower the option_
but that breaks the principle of _sensible defaults_ (aka no surprises).
The fact that you can sidestep the bullet does not mean you're not creating
a footgun.
When you need a millimeter option, reach for a [snapped
percentage option][1] instead.
:::
[1]: /reference/api/part/config/options/pct
ab3204f9f1