Pixel to REM Converter
Convert CSS pixel values to responsive rem units. Essential tool for modern web development.
Pixel Values (Input)
Enter numbers, one per line or space-separated. CSS declarations are also supported.
REM Values (Output)
Calculated using: 1rem = 16px
Common Conversions
What is a Pixel to REM Converter?
A Pixel to REM Converter is an essential tool for modern web developers and designers working with responsive CSS. It converts static pixel values into relative REM units, which scale proportionally based on the user's browser settings and device characteristics.
This tool helps you create more accessible and flexible websites by automating the conversion process. Simply enter your pixel values, set your base font size, and get instant REM calculations.
Why Use REM Units in CSS?
REM (Root EM) units are relative to the root element's font size, making them perfect for responsive design:
| Feature | Pixels (PX) | REM Units |
|---|---|---|
| Accessibility | Ignores user's browser font size settings | Respects user preferences for larger/smaller text |
| Responsiveness | Fixed size, doesn't scale with root font changes | Scales proportionally with root font size changes |
| Consistency | Absolute measurement (1px = 1/96th inch) | Relative to root element (1rem = root font size) |
| Maintenance | Requires manual adjustments for different breakpoints | Change root size to scale entire layout proportionally |
How to Convert Pixels to REM
The conversion formula is straightforward:
rem = pixel_value / base_font_sizeExample Calculations:
- With base 16px:
24px = 24 / 16 = 1.5rem - With base 10px:
24px = 24 / 10 = 2.4rem - With base 20px:
24px = 24 / 20 = 1.2rem
Common Use Cases
1. Responsive Typography
/* Instead of fixed pixels */
h1 { font-size: 32px; }
h2 { font-size: 24px; }
/* Use REM for scalability */
html { font-size: 16px; }
h1 { font-size: 2rem; } /* 32px at 16px base */
h2 { font-size: 1.5rem; } /* 24px at 16px base */2. Spacing and Layout
/* Fixed spacing */
.container { padding: 20px; }
.item { margin-bottom: 15px; }
/* Responsive spacing */
.container { padding: 1.25rem; } /* 20px at 16px base */
.item { margin-bottom: 0.9375rem; } /* 15px at 16px base */3. Media Queries with REM
/* Using pixels */
@media (min-width: 768px) { ... }
/* Using REM (better for zooming) */
@media (min-width: 48rem) { ... } /* 768px at 16px base */Best Practices for Using REM
- Set Base Font Size in HTML: Always define your base font size on the
htmlelement, not thebody. - Use Percentage for Root: Set
html { font-size: 62.5%; }to make 1rem = 10px for easier calculations. - Combine with Media Queries: Adjust root font size at different breakpoints for truly responsive scaling.
- Fallback for Old Browsers: Provide pixel fallbacks for browsers that don't support REM.
Frequently Asked Questions (FAQ)
What's the difference between EM and REM?
EM units are relative to their parent element's font size, while REM units are always relative to the root (html) element's font size. REM provides more predictable results as it's not affected by nested font-size declarations.
Should I use REM for everything?
While REM is excellent for most sizing, border widths and very small measurements are often better in pixels. Also, use percentages for widths and viewport units (vw/vh) for full-viewport elements.
How do I handle browser zoom with REM?
REM units naturally support browser zoom because they're relative to the root font size. When users zoom in, the browser increases the base font size, and all REM-based measurements scale proportionally.
Can I convert REM back to pixels?
Yes! Our tool supports bidirectional conversion. Use the "Convert to Pixels" button to convert REM values back to pixel values based on your current base font size setting.