What is a CSS Unit Converter?
This tool converts px values into rem, em, and percentages using your base font size.
It helps standardize scalable typography and spacing in responsive front-end systems.
How to use
- Enter your source pixel value.
- Set the base font size used in your project.
- Read rem, em, and percent equivalents.
- Copy the result you need into your CSS.
Example usage
Convert 24px heading size into rem to align with a root font-size based design system.
Tips
- Keep one base font-size across the project for consistency.
- Use rem for typography tokens.
- Use percentages when adapting relative sizing contexts.
- Document converted values in your style guide.
FAQ
- What base size should I use?
- Most projects start with 16px, but use your own root setup if different.
- Are rem and em always the same?
- They match only when parent font-size equals root font-size.
- Can I use this for spacing too?
- Yes, the same conversion logic applies to padding and margin values.