PX to REM / EM Converter
Convert pixel values to rem and em instantly with our free px to rem em converter. Supports all four directions - px→rem, rem→px, px→em, em→px - with configurable root and parent font sizes. Includes a reference table for common pixel values. No signup required - all conversions run locally in your browser.
Enter a value, choose a conversion direction, and configure the root font size (for rem) or parent font size (for em). All conversions run instantly in your browser with a full reference table for common pixel values.
| px | rem (16px root) | em (16px parent) |
|---|---|---|
| 4 | 0.25 | 0.25 |
| 8 | 0.5 | 0.5 |
| 12 | 0.75 | 0.75 |
| 14 | 0.875 | 0.875 |
| 16 | 1 | 1 |
| 18 | 1.125 | 1.125 |
| 20 | 1.25 | 1.25 |
| 24 | 1.5 | 1.5 |
| 32 | 2 | 2 |
| 48 | 3 | 3 |
| 64 | 4 | 4 |
| 96 | 6 | 6 |
Why Use Our PX to REM / EM Converter?
Instant PX to REM / EM Conversions
Convert pixel values to rem and em instantly in your browser with zero wait time. Our px to rem em converter handles all four directions - px→rem, rem→px, px→em, em→px - in milliseconds with a full reference table.
Secure PX to REM Converter Online
All px to rem and em conversions happen locally in your browser - your values never leave your device. Use our px to rem em converter online with complete privacy and zero data collection.
PX to REM Converter Online - No Installation
Use our px to rem em converter directly in any browser with no downloads, plugins, or app installs required. Convert pixel values from any device, anywhere, instantly.
Configurable Root & Parent Font Size
Our px to rem em converter lets you set any root font size for rem conversions and any parent font size for em conversions. Choose from common presets (14px, 16px, 18px, 20px) or enter a custom value.
Common Use Cases for PX to REM / EM Converter
Responsive Web Design
Convert fixed pixel values to rem units to create scalable, accessible layouts that respect user font size preferences. Use our px to rem converter to migrate pixel-based designs to fluid, responsive CSS.
CSS Typography Scaling
Set font sizes in rem to ensure text scales proportionally with the root font size. Our px to rem em converter helps you translate design specs in pixels to the correct rem values for consistent typography.
Component-Level Spacing with EM
Use em units for padding and margins that scale relative to the component's own font size. Our px to em converter calculates the correct em value based on any parent font size for component-scoped spacing.
Accessibility & WCAG Compliance
WCAG guidelines recommend using relative units like rem for font sizes to support browser zoom and user font preferences. Our px to rem converter helps developers build accessible interfaces that meet WCAG 1.4.4 requirements.
Design System Development
Design systems use rem-based spacing scales (e.g. 0.25rem, 0.5rem, 1rem, 1.5rem). Use our px to rem em converter to translate pixel values from Figma or Sketch designs into the correct rem tokens for your design system.
CSS Framework Customization
Tailwind CSS, Bootstrap, and other frameworks use rem-based sizing. Use our px to rem converter to calculate the correct rem values when customizing breakpoints, spacing scales, and typography in CSS frameworks.
Understanding PX, REM, and EM Units
What are PX, REM, and EM?
In CSS, px (pixels) are absolute units - 16px is always 16px regardless of any other setting. rem (root em)is a relative unit based on the root element's font size (the <html> element). If the root font size is 16px, then 1rem = 16px, 1.5rem = 24px, and 0.5rem = 8px. em is also a relative unit, but it is relative to the parent element's font size rather than the root. If a parent element has a font size of 20px, then 1em = 20px within that element. Our px to rem em converter handles all four conversion directions - px→rem, rem→px, px→em, em→px - with configurable root and parent font sizes.
How Our PX to REM / EM Converter Works
- 1. Configure Font Sizes: Set the root font size for rem conversions (default 16px, the browser default) and the parent font size for em conversions. Choose from common presets or enter a custom value. All processing happens locally in your browser - your data never leaves your device.
- 2. Choose Direction and Enter Value: Select px→rem, rem→px, px→em, or em→px from the direction dropdown. Use the swap button to instantly reverse the direction. Enter your value and click Convert.
- 3. View Results and Reference Table: The result is displayed instantly with a copy button. A reference table shows common pixel values (4px to 96px) converted to both rem and em at your configured font sizes for quick lookup.
Conversion Formulas
- PX to REM: rem = px ÷ root font size. Example: 24px ÷ 16px = 1.5rem.
- REM to PX: px = rem × root font size. Example: 1.5rem × 16px = 24px.
- PX to EM: em = px ÷ parent font size. Example: 24px ÷ 20px = 1.2em.
- EM to PX: px = em × parent font size. Example: 1.2em × 20px = 24px.
REM vs EM: When to Use Each
Use remfor global sizing that should scale with the user's browser font size preference - font sizes, spacing scales, and layout dimensions. Rem is predictable because it always references the root, avoiding the compounding effect of nested em values. Use emfor component-scoped sizing where you want elements to scale relative to their container's font size - padding, margins, and icon sizes within a component. Em is powerful for self-contained components but can compound unexpectedly in deeply nested elements. The browser default root font size is 16px, which is why 1rem = 16px in most browsers unless the user or developer changes it.
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Frequently Asked Questions About PX to REM / EM Converter
What is a PX to REM converter?
A px to rem converter translates pixel values to rem units based on a configurable root font size. Our px to rem em converter supports all four directions - px→rem, rem→px, px→em, em→px - with a reference table for common values, all running instantly in your browser.
What is the formula for converting px to rem?
rem = px ÷ root font size. With the default browser root font size of 16px: 16px = 1rem, 24px = 1.5rem, 32px = 2rem. Our px to rem converter applies this formula instantly for any root font size you configure.
What is the difference between rem and em?
rem is relative to the root element font size (always the <html> element), while em is relative to the parent element's font size. Rem is more predictable for global sizing; em is useful for component-scoped sizing that should scale with its container.
What root font size should I use?
The browser default root font size is 16px, which is the most common setting. Some designers use 10px as the root size to make rem math easier (1rem = 10px, so 1.6rem = 16px). Our px to rem converter supports any root font size from the presets or a custom value.
Why should I use rem instead of px for font sizes?
Using rem for font sizes respects the user's browser font size preference, improving accessibility. If a user sets their browser to 20px base font size, rem-based text scales accordingly while px-based text stays fixed. This is required for WCAG 1.4.4 compliance.
Can I convert em to px with this tool?
Yes! Select "em → px" from the direction dropdown, set your parent font size, enter your em value, and click Convert. The tool calculates px = em × parent font size. Use the swap button to quickly reverse between px→em and em→px.
Is this PX to REM converter free to use?
Yes! Our px to rem em converter is 100% free with no signup, no ads, and no usage limits. Convert pixel values as many times as you need - completely free, forever.
Is my data safe when using this PX to REM converter?
Absolutely. All conversions happen locally in your browser using JavaScript. Your values are never sent to any server, ensuring complete privacy every time you use our px to rem em converter online.
What does the reference table show?
The reference table shows common pixel values (4px, 8px, 12px, 14px, 16px, 18px, 20px, 24px, 32px, 48px, 64px, 96px) converted to both rem and em at your configured font sizes. The currently converted value is highlighted for quick reference.