Free CSS Unit Converter
Seamlessly convert pixels to REMs, EMs to percentages, and more. A must-have tool for responsive web design.
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CSS Unit Converter
PX
%
PT
EM
REM
Why Standards Matter
Modern web development relies on scalable units. While PX is absolute, units like EM and REM are relative, making your design accessible and responsive across devices.
Supported Conversions:
- PX to REM (Root EM)
- PX to EM (Element EM)
- PX to % (Percentage)
- PX to PT (Points)
- REM to PX
- EM to PX
Pro Tip: Set your root font size to 62.5% (10px) in CSS. This makes 1rem = 10px, simplifying calculations while keeping accessibility intact!
How to Convert CSS Units
Step 1: Enter a Value
Type a number in any CSS unit — PX, EM, REM, %, or PT.
Step 2: Set Base Font Size
Configure the root font size (default 16px) for accurate EM/REM calculations.
Step 3: Copy Converted Values
All unit equivalents update in real-time. Copy the one you need.
Frequently Asked Questions
EM is relative to the parent element's font size, while REM is relative to the root (html) element's font size. REM is more predictable and recommended for most use cases.
REM respects the user's browser font-size settings, making your design more accessible. If a user sets their browser to 20px base, REM-based designs scale properly.
Most browsers default to 16px. So 1rem = 16px by default. You can change this with `html { font-size: 62.5% }` to make 1rem = 10px for easier math.
Use percentage for widths, max-widths, and flexible layouts. For font sizes, REM is usually a better choice as percentages can compound unpredictably in nested elements.