Convert Between CSS Units Like px, em, rem, %, vw, and vh
Easily convert CSS units for responsive web design and development. Perfect for creating scalable, flexible layouts.
Select units to convert and enter values to see the conversion explanation here.
A CSS Unit Converter is a powerful online tool that allows web designers and developers to easily convert between different CSS units of measurement. CSS units are essential for creating responsive, scalable web designs that work across various devices and screen sizes. This tool simplifies the process of converting between absolute units (like pixels) and relative units (like em, rem, percentages, and viewport units).
Get immediate conversion results as you enter values
Support for all major CSS units including px, em, rem, %, vw, vh, and more
Perfect for creating flexible, scalable layouts for all devices
CSS units define the size, length, or dimension of HTML elements. Understanding the different types of units and when to use them is crucial for creating responsive web designs that adapt to various screen sizes and user preferences.
CSS units can be categorized into several types, each serving different purposes in web design:
| Unit Type | Units | Description |
|---|---|---|
| Absolute Units | px, pt, pc, in, cm, mm | Fixed-size units that appear as exactly that size |
| Relative Units | em, rem, %, ex, ch | Units relative to another value (font size, parent element, etc.) |
| Viewport Units | vw, vh, vmin, vmax | Units relative to the viewport dimensions |
When working with CSS units, follow these best practices for optimal results:
rem for font sizes to ensure consistent scalingem for spacing related to font size% for container widths and responsive layoutsvw/vh for full-screen or viewport-relative sizinghtml element for consistent rem calculationsHere are some frequently needed conversions and their formulas:
CSS units have excellent browser support across modern browsers, making them safe to use in production websites:
| Unit | Support | Notes |
|---|---|---|
| px | Universal | Supported in all browsers |
| em | Universal | Supported in all browsers |
| rem | IE9+ | Excellent modern browser support |
| % | Universal | Supported in all browsers |
| vw/vh | IE9+ | Good modern browser support |
| vmin/vmax | IE10+ | Good modern browser support |
Converting CSS units with our online tool is simple and efficient:
Type the numerical value you want to convert in the "Value to Convert" field.
Choose the unit you're converting from in the "From Unit" dropdown (e.g., px, em, rem).
Choose the unit you want to convert to in the "To Unit" dropdown.
Enter relevant context values like base font size and viewport dimensions when needed.
Click "Convert" to see the conversion result, visual preview, and detailed explanation.
Beyond basic unit conversions, CSS units offer advanced capabilities for creating sophisticated responsive designs:
Combine relative units with CSS functions to create fluid typography that scales smoothly across viewport sizes.
Use relative units with container queries to create components that adapt to their container size rather than viewport.
Use relative units to create harmonious typographic scales that maintain proportions across different contexts.
This CSS Unit Converter tool is built using modern web technologies to provide accurate and reliable unit conversions:
Convert fixed pixel values to relative units to create layouts that adapt to different screen sizes and user preferences.
Ensure text and elements scale properly for users who adjust their browser's default font size.
Convert design specifications to appropriate CSS units for consistent implementation across components.
Update older websites with fixed pixel values to use modern, scalable relative units.
The em unit is relative to the font-size of the parent element, while the rem unit is relative to the root (html) element's font-size. This makes rem more predictable and easier to manage in complex layouts.
Viewport units (vw, vh, vmin, vmax) are ideal for full-screen layouts, hero sections, and elements that should scale with the viewport size. They're particularly useful for creating responsive designs that maintain proportions across devices.
To convert pixels to em, divide the pixel value by the parent element's font-size. For example, if you want 16px text inside an element with 12px font-size: 16 ÷ 12 = 1.33em.
For responsive typography, rem is generally preferred for font sizes because it's consistent and scales with user preferences. Combine with CSS functions like clamp() for fluid typography that adapts smoothly across viewport sizes.
Follow these guidelines to effectively implement CSS units in your projects:
html element (typically 16px)rem and % for scalable, responsive designsOur online CSS Unit Converter tool offers several advantages over other solutions:
Explore these common unit conversions to understand the relationships between different CSS units:
The CSS Unit Converter is an essential tool for web designers and developers working with responsive layouts and scalable designs. By providing an easy way to convert between different CSS units, it helps ensure consistency across projects and simplifies the process of creating flexible, accessible web experiences.
Whether you're building a new responsive website, updating legacy code, or fine-tuning a design system, this tool provides everything you need to work with CSS units effectively. Remember to always consider the context and relationship between elements when choosing units, and test your designs across different devices and viewport sizes.
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