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A pixel or rem value and the root font size.
Quick math
PX ↔ REM converter
Translate design measurements without hiding the formula.
Privacy built inYour work stays with you
Converted value
1rem
1remYour work stays private in your browser while you use this tool.
What does px ↔ rem converter do?
The px/rem converter divides pixels by the root font size to get rem, or multiplies rem by the root font size to get pixels. With the common 16 px root, 1 rem equals 16 px.
- Input
- A pixel or rem value and the root font size.
- Result
- Equivalent px and rem measurements.
- Price
- Free
- Account
- Not required
How to use px ↔ rem converter
Choose your settings
Translate design measurements without hiding the formula.
Save or copy
Equivalent px and rem measurements.
A practical tip
Most browsers default to a 16px root size, but your project may set a different value.
When to use px ↔ rem converter
Translate a 24 px design-system spacing value into rem for CSS.
Check the pixel equivalent of a 1.125 rem type size at a custom root size.
Migrate a stylesheet from fixed pixel lengths to root-relative units.
Worked example
A concrete px ↔ rem converter example
- Input
- 24 px
- Settings
- Root font size: 16 px; pixels to rem
- Result
- 1.5 rem
What to expect
How it works
For px to rem, the value is divided by the positive root font size. For rem to px, it is multiplied by that size. Results retain useful decimal precision and can be copied with the output unit.
Know before using
Limits and edge cases
- The calculator does not inspect your page's computed root font size; you must enter the value that applies to your CSS environment.
- It performs a numeric conversion only and does not account for browser minimum-font preferences, zoom, or root sizes that change across media queries.
Standards and sources
Common questions
PX ↔ REM converter FAQ
Is px ↔ rem converter free to use?
Yes. PX ↔ REM converter is free to use.
Does px ↔ rem converter keep my work private?
Yes. Your work stays private while you use the tool — nothing you enter is uploaded.
What root font size should I enter?
Enter the computed font size of the document's root element for the context you are targeting. Many projects use 16 px, but it is not guaranteed.
Is rem the same as em?
No. rem is relative to the root element's font size, while em is generally relative to the element's own computed font size. This calculator handles rem only.