PX to REM Converter
CSS units conversion tool
Pixels (px)
REM
Visual Size Comparison
Quick Tips
Default Base Size
Most browsers use 16px as the default root font size
Responsive Design
REM units scale with root font size, perfect for responsive design
Accessibility
REM respects user's browser font size settings for better accessibility
CSS Usage
Use REM for font-size, padding, margin, and other spacing properties
Common PX to REM Conversions (Base: 16px)
| Pixels (px) | REM | Common Use |
|---|---|---|
| 8px | 0.5rem | Small icons, thin borders |
| 10px | 0.625rem | Small text, captions |
| 12px | 0.75rem | Small labels, meta text |
| 14px | 0.875rem | Body text (small) |
| 16px | 1rem | Default body text |
| 18px | 1.125rem | Large body text |
| 20px | 1.25rem | Subheadings |
| 24px | 1.5rem | H3 headings |
| 28px | 1.75rem | H2 headings |
| 32px | 2rem | H2 headings (large) |
| 36px | 2.25rem | H1 headings |
| 48px | 3rem | Hero headings |
| 64px | 4rem | Display text |
| 72px | 4.5rem | Large display |
| 96px | 6rem | Hero display |
REM to PX Conversions (Base: 16px)
| REM | Pixels (px) | Common Use |
|---|---|---|
| 0.25rem | 4px | Tiny spacing |
| 0.5rem | 8px | Small padding/margin |
| 0.75rem | 12px | Compact spacing |
| 1rem | 16px | Base spacing unit |
| 1.5rem | 24px | Section spacing |
| 2rem | 32px | Large spacing |
| 3rem | 48px | Section margins |
| 4rem | 64px | Page margins |
| 5rem | 80px | Hero spacing |
| 6rem | 96px | Large section gaps |
| 8rem | 128px | Page sections |
| 10rem | 160px | Major sections |
REM Usage Tips
Design Systems
Use REM for consistent spacing in design systems and component libraries
Mobile First
REM scales with root font size, making mobile-first responsive design easier
Accessibility
Users can adjust browser font size, and REM-based designs will scale accordingly
Easy Math
With 16px base, divide px by 16 to get rem. Example: 24px ÷ 16 = 1.5rem
Understanding PX and REM Units
What is PX (Pixel)?
Pixel (px) is an absolute unit of measurement in CSS. It represents a single dot on the screen and does not scale with user preferences or parent element sizes. Pixels provide precise control but can cause accessibility issues.
What is REM?
REM (Root EM) is a relative unit that is relative to the root element's (html) font size. By default, most browsers set the root font size to 16px, so 1rem = 16px. REM units scale with the user's browser settings, making them more accessible.
Conversion Formula
The formula to convert between PX and REM:
- PX to REM: REM = PX ÷ Base Font Size
- REM to PX: PX = REM × Base Font Size
- Default Base: 16px (browser default)
- Example: 24px ÷ 16 = 1.5rem
CSS Examples
How to use REM in CSS:
font-size: 1rem;(equals 16px)padding: 1.5rem;(equals 24px)margin: 2rem 1rem;(32px top/bottom, 16px left/right)gap: 0.5rem;(equals 8px)
PX vs REM: When to Use Each
Both units have their place in web development:
- Use REM for: Font sizes, padding, margins, and spacing that should scale
- Use PX for: Borders, box-shadows, and elements that should stay fixed
- Best Practice: Use REM for most spacing and sizing, PX for fine details
Accessibility Benefits
REM units improve accessibility because:
- They respect the user's browser font size settings
- Users with visual impairments can increase base font size
- Content scales proportionally across the entire page
- Better support for high-DPI displays
Best Practices
Set Base Font Size
Set html { font-size: 16px; } as your base for consistent REM calculations
Responsive Typography
Use media queries to adjust root font size for different screen sizes
Use CSS Variables
Define common REM values as CSS variables for easy maintenance
Use This Tool
Quickly convert PX to REM when writing CSS to ensure consistency
Understanding PX to REM Conversion
Converting pixels (px) to REM is essential for modern responsive web design. REM (Root EM) is a relative CSS unit that scales with the root element's font size, making it more flexible and accessible than fixed pixel values. Most browsers default to 16px as the root font size, making 1rem equal to 16px.
Conversion Formula
The formula for converting between pixels and REM:
- PX to REM: REM = PX ÷ Base Font Size (default 16px)
- REM to PX: PX = REM × Base Font Size
- Example: 24px ÷ 16 = 1.5rem
- Example: 2rem × 16 = 32px
Why Use REM?
REM units offer several advantages over pixels:
- Accessibility: REM respects user's browser font size settings
- Responsive Design: Scales proportionally with root font size changes
- Consistency: Easier to maintain consistent spacing across components
- Maintainability: Change root font size to scale entire design
- Best Practice: Recommended by modern CSS frameworks and design systems
Common Use Cases
Common scenarios where PX to REM conversion is useful:
- Typography: Converting font sizes from design mockups (usually in px) to REM
- Spacing: Converting padding and margin values for responsive layouts
- Component Libraries: Building scalable component libraries with REM units
- Design Systems: Creating consistent design tokens in REM
- Accessibility: Ensuring text scales properly for users with visual impairments
Using This Converter
Follow these steps:
- Step 1: Select your base font size (default is 16px)
- Step 2: Enter a value in either the PX or REM field
- Step 3: The conversion happens automatically in real-time
- Step 4: Use the swap button to reverse the conversion direction
- Step 5: View the visual size comparison for context
- Step 6: Check the Reference Table for common conversions
- Step 7: Read the Guide tab to learn more about REM units
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