Our advanced CSS Unit Converter helps developers and designers accurately convert between all CSS measurement units. Whether you’re working with px, em, rem, or viewport units, get instant and precise results. Perfect for responsive design, accessibility compliance, and cross-browser consistency.
Live CSS Unit Conversion
Advanced Settings
Privacy Guaranteed: All conversions happen locally in your browser. No data is sent to our servers.
Why Use a CSS Unit Converter?
In modern web development, a reliable unit converter is an indispensable tool for several reasons:
- Streamline Responsive Design: Quickly convert static
pxvalues from a design mockup into flexibleremor%units for a fluid layout. - Enhance Accessibility: Easily switch to relative units like
rem, which respect a user’s browser font size settings, making your website more accessible. - Maintain Consistency: Ensure consistent spacing and typography across your project by standardizing on a single relative unit like
rem. - Save Time and Reduce Errors: Manual calculations are slow and prone to error. A converter provides instant, accurate results.
A Comprehensive Guide to CSS Units
Understanding the difference between absolute and relative units is fundamental to modern CSS.
Relative Units (Recommended)
Rems (rem)
Relative to the root (html) element’s font size. Best for overall layout and font-size consistency.
Ems (em)
Relative to the parent element’s font-size. Good for properties that should scale with their local context.
Percentage (%)
Relative to the parent element’s size. Essential for creating fluid grid columns.
Viewport (vw/vh)
1vw = 1% of the viewport’s width. Excellent for creating full-width banners or responsive typography.
Absolute Units
Pixels (px)
A fixed unit. Useful for things that should never scale, like a 1px border or a specific box-shadow.
Points (pt)
A standard typography measurement where 1pt = 1/72 of an inch. Primarily used for print stylesheets.
CSS Unit Conversion Reference
This table shows common conversions based on a default browser setting of font-size: 16px and a standard screen resolution of 96 DPI.
| Unit | Equivalent to 16px | Primary Use Case |
|---|---|---|
| 1em | 16px (in default context) | Relative to current font size |
| 1rem | 16px | Relative to root font size |
| 100% | 16px (for font-size) | Relative to parent element |
| 1pc | 16px | Print typography (12 points) |
| 1.2vw | ~16px on a 1366px screen | Scaling with viewport width |
| 1in | 96px | Print layouts, physical measurements |
| 2.54cm | 96px | Print styles, physical measurements |
| 12pt | 16px | Print typography (1/72 inch) |
Frequently Asked Questions
Use rem for global sizing (margins, padding, typography) for site-wide consistency. Use em for sizing within a component that should scale relative to the component’s own font-size.
Using vw alone is an accessibility issue. A better approach is the CSS clamp() function, like font-size: clamp(1rem, 2.5vw, 1.5rem);. This creates responsive text that also respects user settings.
The % unit is relative to the dimensions of the parent element. The vw unit is relative to the width of the browser window itself, regardless of its parent’s size.
This converter promotes accessibility by making it easy to convert fixed px units to relative units like rem. Relative units respect a user’s choice to increase their default font size, ensuring your site is readable for everyone.