What's the difference between em and rem?

rem is relative to the root font size (html), while em is relative to the parent element's font size. rem is more predictable.

What base font size should I use?

Browser default is 16px. Most calculations assume this, but you can adjust it to match your project's root font size.

Why use rem instead of px?

rem respects user browser preferences for accessibility and makes responsive scaling easier.

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CSS Unit Converter

Convert between px, em, rem, and %

Base Font Size (px):

Pixels

16px

REM

1rem

1em

Percent

100%

Calculation based on 16px base size

About CSS Unit Converter

What is CSS Unit Converter?

Convert between CSS units for responsive web design. Transform pixels to rem, em to pixels, percentages, and viewport units. Set your base font size and get accurate conversions for consistent responsive layouts.

Features & Benefits

Convert px, em, rem, % units
Viewport units (vw, vh) support
Customizable base font size
Bidirectional conversion
Copy CSS values directly
Essential for responsive design

Frequently Asked Questions

What's the difference between em and rem?: rem is relative to the root font size (html), while em is relative to the parent element's font size. rem is more predictable.
What base font size should I use?: Browser default is 16px. Most calculations assume this, but you can adjust it to match your project's root font size.
Why use rem instead of px?: rem respects user browser preferences for accessibility and makes responsive scaling easier.

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How-To Guides

How to Convert px to rem

Guides

Convert CSS Units Online Free PX to REM Converter in Your Browser

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