REM → MM Converter
Converting from REM to MM is common when switching from useful for typography scaling and accessibility. to for ultra-precise graphic designs. in CSS projects.
Conversion Form
About the Unit
REM (Root EM): REM is a relative unit that depends on the root font size, typically defined in the `<html>` element of the document. The main advantage of REM is that it provides a consistent and scalable way to work with measurement units in web design, especially when creating responsive and accessible layouts. When you define the root font size, for example, as 16px, 1rem will be equivalent to 16px. If the root font size is changed, all measurements in rem will adjust proportionally, which makes controlling the layout as a whole easier. This is especially useful for ensuring that the design is consistent and accessible, as users can adjust the font size in the browser. Using rem instead of px helps maintain the layout's proportions when scaling the page globally without needing to adjust each value individually.
Pro Tip: rem → mm
For precise print layouts, convert rem to mm for print precision.
Quick Reference: Unit Conversion by Tens
| REM | MM |
|---|---|
| 10rem | 42.333333mm |
| 20rem | 84.666667mm |
| 30rem | 127mm |
| 40rem | 169.333333mm |
| 50rem | 211.666667mm |
| 60rem | 254mm |
| 70rem | 296.333333mm |
| 80rem | 338.666667mm |
| 90rem | 381mm |
| 100rem | 423.333333mm |
| 110rem | 465.666667mm |
| 120rem | 508mm |
| 130rem | 550.333333mm |
| 140rem | 592.666667mm |
| 150rem | 635mm |
| 160rem | 677.333333mm |
| 170rem | 719.666667mm |
| 180rem | 762mm |
| 190rem | 804.333333mm |
| 200rem | 846.666667mm |
| 210rem | 889mm |
| 220rem | 931.333333mm |
| 230rem | 973.666667mm |
| 240rem | 1016mm |
| 250rem | 1058.333333mm |
Live Unit Preview
See how different CSS units affect the size of the box below:
10px
10rem
10em
10%
10vw
10vh
Common Mistake
For precise print layouts, convert rem to mm for print precision.
Real Code Example
/* Mobile-first card with rem → mm */
.card {
padding: 0rem; /* undefinedmm */
font-size: 1.5rem;
width: min(90vw, 40ch);
}Frequently Asked Questions About REM
When should I use rem instead of rem?
Use rem for consistent scaling across components.
How many rem is 1rem?
1rem = 16px by default.
Is rem affected by zoom?
Yes, it scales with user settings and zoom.
Is rem good for fonts?
Yes, it's preferred for accessibility.
Keyboard Shortcuts
- Ctrl + C: Convert
- Ctrl + I: Invert units
- Esc: Reset values