CM to REM Converter
Conversion Guide
1. Convert cm to px (multiply by ~37.8). 2. Convert px to rem. Example: 0.423cm ≈ 16px = 1rem
CM to REM Conversion Table
| CM | REM | Actions |
|---|---|---|
| 0.42333 | 1 | |
| 0.846666 | 2 | |
| 1.27 | 3 | |
| 2.54 | 6 | |
| 3.81 | 9 | |
| 5.08 | 12 | |
| 7.62 | 18 | |
| 10.16 | 24 |
Frequently Asked Questions
Basics
What is CM?
Centimeters (cm) are absolute-length units that correspond to physical centimeters, commonly used in print design and European markets.
How do cm units compare to other length units?
1cm equals 10mm or approximately 37.8px (at 96 DPI). For web design, relative units like rem are generally preferred.
When are cm units most appropriate?
cm units are most appropriate for print stylesheets or when precise physical measurements are needed in metric units.
What is REM?
The rem (root em) unit is a relative unit that's always based on the font-size of the root element (html). This makes it powerful for creating consistent, scalable layouts that respect user preferences. Unlike em units which compound in nested elements, rem always refers back to the root font-size.
Why should I use rem instead of pixels?
REM units provide better accessibility by respecting user font size preferences, maintain consistent scaling across the site, and simplify responsive design. Unlike pixels, rem units scale proportionally when users change their browser's font size settings.
How do I calculate rem values from pixels?
To convert pixels to rem, divide the desired pixel value by the root font size (typically 16px). For example: 32px ÷ 16px = 2rem. Many code editors and dev tools can do this calculation automatically.
What's the difference between rem and em units?
While both are relative units, em is relative to the font-size of the current element or its closest parent with a defined font-size. rem is always relative to the root element, making it more predictable for layout and preventing compound scaling issues.
When should I use rem vs em units?
Use rem for consistent spacing, layout and general typography. Use em when you want elements to scale relative to their parent's font size, like padding in buttons or line-height in paragraphs.
How can I debug rem calculations?
Most browser dev tools can show both rem and pixel values. You can also set a more convenient root font-size (like 10px) to make calculations easier: html { font-size: 62.5%; } (making 1rem = 10px)
Conversion
How to convert CM to REM?
To convert CM to REM, use the following formula:
cm * 37.8 / root font size