PX to REM Converter
Convert pixels to REM units instantly with this free online tool. Perfect for responsive web design. Input any pixel value, set your base font size, and get accurate REM results in real-time.
What Are PX and REM Units?
Pixels (px) are fixed units commonly used in web design. A pixel represents a single dot on the screen and does not scale based on user preferences.
REM (Root EM) is a relative CSS unit that is based on the root font size of the document, usually defined on the <html> element. By default, most browsers use a root font size of 16px.
Because REM units are relative, they allow designs to scale consistently when users change browser font size or when layouts adapt to different screen sizes.
Why Convert PX to REM?
Converting pixels to REM is a common best practice in modern web development. REM units help create layouts that are more flexible, accessible, and easier to maintain.
- Improves accessibility for users who increase font size
- Creates scalable and responsive layouts
- Makes typography more consistent across components
- Reduces layout breakage on different devices
- Recommended by modern CSS frameworks
How to Use Our PX to REM Calculator
Follow these simple steps to convert pixel values into REM units using our calculator:
- Enter the pixel (px) value you want to convert.
- Set the base font size (default is 16px).
- The calculator instantly displays the REM value.
- Copy the result and use it directly in your CSS.
Instead of calculating values manually, our PX to REM converter helps you convert values quickly and confidently.
PX to REM Conversion Formula
The formula used to convert PX to REM is:
REM = PX ÷ Base Font Size
The base font size is usually 16px, unless you have defined a different value in your CSS.
PX to REM Conversion Examples
Here are some common examples using a base font size of 16px:
- 16px ÷ 16 = 1rem
- 24px ÷ 16 = 1.5rem
- 32px ÷ 16 = 2rem
- 40px ÷ 16 = 2.5rem
Common Use Cases for PX to REM
PX to REM conversion is widely used in modern frontend development for many practical reasons:
- Responsive typography that adapts to screen size
- Accessible layouts that respect user font settings
- Design systems and component libraries
- Converting fixed designs into scalable CSS
- Mobile-first and responsive web projects
PX vs REM: Which Should You Use?
PX units are useful when you need precise, fixed sizing. However, REM units are preferred when building layouts that need to scale consistently.
In most modern projects, developers use REM for font sizes, spacing, and layout measurements, while PX may still be used for borders or very small elements.
Frequently Asked Questions (FAQs)
What is the default base font size for REM?
The default base font size in most browsers is 16px. However, this can be changed by defining a different font size on the html element.
Is REM better than PX?
REM is generally better for responsive and accessible designs because it scales based on user preferences. PX is fixed and does not adapt.
Does REM affect website performance?
No, using REM units does not negatively affect performance. It is fully supported by modern browsers.
Can I mix PX and REM in the same project?
Yes. Many developers use REM for typography and spacing, while using PX for borders or very small fixed elements.
What happens if I change the root font size?
If you change the root font size, all REM-based values will scale accordingly. This makes global adjustments much easier.
Disclaimer: PX to REM conversion depends on the root font size defined in your CSS. Results may vary if a custom base font size is used or if user browser settings differ.