PX to REM Converter
This PX to REM converter transforms pixel values into REM units for responsive CSS. REM units scale relative to the root font size (default 16px), so 16px = 1rem. Enter any pixel value and base font size to get the equivalent REM value instantly.
PX to REM Converter
Convert pixel (px) values to rem units based on the root element font size
Frequently Asked Questions
What is the formula to convert PX to REM?
The formula to convert PX to REM is: REM = pixel value ÷ base font size. The default base font size in browsers is 16px. For example, to convert 24px to REM: 24 ÷ 16 = 1.5rem. Other common conversions: 12px = 0.75rem, 14px = 0.875rem, 16px = 1rem, 20px = 1.25rem, 32px = 2rem, and 48px = 3rem. If your project uses a different base font size, substitute that value in the formula.
What is the default base font size in browsers?
The default base font size in all major web browsers (Chrome, Firefox, Safari, Edge) is 16px. This means that without any CSS overrides, 1rem equals 16px. This 16px default has been the standard since the early days of the web and is the value most PX to REM converters use by default. Some developers override this with 'html { font-size: 62.5%; }' to set a 10px base, making conversions simpler (1rem = 10px), but this can cause accessibility issues if not handled carefully.
What is the difference between PX and REM?
PX (pixels) is an absolute CSS unit that renders at a fixed size regardless of user settings or parent elements. REM (root em) is a relative unit based on the root element's font size, typically the <html> element. If the root font size is 16px, then 1rem equals 16px. The key difference is that REM scales when users change their browser's default font size for accessibility, while PX stays fixed. This makes REM the preferred unit for responsive and accessible web design.
Why should I use REM instead of PX?
REM units scale with user font preferences, improving accessibility for visually impaired users. When a user increases their browser's default font size, REM-based layouts scale proportionally while PX-based layouts remain fixed. REM also improves maintainability: changing the root font size in one place scales your entire design proportionally. Additionally, REM units combined with media queries make it easier to create responsive layouts that adapt to different screen sizes. WCAG 2.1 guidelines recommend using relative units for text sizing.
What is the difference between REM and EM?
REM (root em) is relative to the root element's font size (the <html> element), while EM is relative to the font size of its parent element. This means REM always produces consistent values regardless of nesting depth, but EM compounds with each level of nesting. For example, if a parent has font-size: 1.5em and a child also has font-size: 1.5em, the child's actual size is 1.5 × 1.5 = 2.25 times the root size. With REM, 1.5rem always equals 1.5 times the root size. REM is generally preferred for its predictability.
When should I use PX instead of REM?
Use PX for values that should remain constant regardless of font size changes. Common cases include: borders (1px borders should stay thin), box-shadows, and certain decorative elements where scaling would look odd. Media query breakpoints are commonly written in PX for consistency, though some developers prefer EM for breakpoints. For all typography, spacing (margin and padding), and layout properties like max-width on containers, REM is generally the better choice for accessibility and responsiveness.
How do I change the base font size?
To change the base font size, set the font-size property on the html element in your CSS. For example, 'html { font-size: 62.5%; }' sets the base to 10px (62.5% of the 16px default), making conversions easier: 1rem = 10px, 1.6rem = 16px. You can also use 'html { font-size: 18px; }' for a larger base. Be cautious with percentage-based values, as they respect user preferences, while fixed pixel values override them. For accessibility, using a percentage is recommended so users who increase their browser font size are not affected.
What is 16px in REM?
16px equals 1rem when using the default root font size of 16px, which is the browser default in all major browsers (Chrome, Firefox, Safari, Edge). The calculation is 16px ÷ 16px = 1rem. If you have changed the root font size to a different value, such as 10px (a common practice), then 16px would equal 1.6rem (16 ÷ 10 = 1.6). Always check your CSS root font size to ensure accurate conversions.
How does REM improve accessibility?
REM improves accessibility by respecting user font size preferences. When a visually impaired user increases the browser's default font size from 16px to 20px, all REM-based text and spacing scales proportionally. A heading set to 2rem would grow from 32px to 40px, maintaining the design hierarchy. With fixed PX values, the text would remain the same size regardless of user settings, effectively ignoring their accessibility needs. WCAG 2.1 guidelines recommend using relative units for text sizing to ensure content remains readable for all users.
About PX to REM Converter
The PX to REM Converter is an essential tool for modern web development that helps developers and designers convert pixel (px) values to relative em (rem) units. Our PX to REM Converter ensures precise calculations for responsive and accessible web designs that scale properly across different devices and user's preferences. Whether you're working on a new project or maintaining existing code, this PX to REM Converter streamlines your workflow.
Why Use Our PX to REM Converter?
The PX to REM Converter simplifies the process of converting pixel measurements to REM units. REM (Root EM) is a relative unit in CSS that references the font size of the root element (html). By default, 1rem equals 16px in most browsers, but our PX to REM Converter allows you to customize this base value for your specific needs. Using REM units instead of pixels creates more flexible and maintainable stylesheets.
How to Use the PX to REM Converter
- Enter your pixel value in the PX to REM Converter's input field
- Set your desired root font size in the PX to REM Converter (default is 16px)
- The PX to REM Converter will instantly calculate and display the equivalent REM value
- Copy the converted REM value to use in your CSS stylesheets
PX to REM Conversion Formula
The PX to REM Converter uses this simple formula for accurate conversions:
REM = pixels ÷ root font size
Example calculations using our PX to REM Converter:
• With 16px base: 24px = 24 ÷ 16 = 1.5rem
• With 16px base: 32px = 32 ÷ 16 = 2rem
• With 10px base: 24px = 24 ÷ 10 = 2.4rem
PX to REM Conversion Table (16px Base)
Reference table for common pixel values and their REM equivalents using the default 16px base font size:
| PX | REM (16px base) | PX | REM (16px base) |
|---|---|---|---|
| 1px | 0.0625rem | 28px | 1.75rem |
| 2px | 0.125rem | 32px | 2rem |
| 4px | 0.25rem | 36px | 2.25rem |
| 8px | 0.5rem | 40px | 2.5rem |
| 10px | 0.625rem | 48px | 3rem |
| 12px | 0.75rem | 56px | 3.5rem |
| 14px | 0.875rem | 64px | 4rem |
| 16px | 1rem | 72px | 4.5rem |
| 18px | 1.125rem | 80px | 5rem |
| 20px | 1.25rem | 96px | 6rem |
| 24px | 1.5rem |
Common Use Cases for PX to REM Converter
- Converting font sizes from pixels to REM for better text scaling
- Transforming margin and padding values for consistent spacing
- Adapting container dimensions for responsive layouts
- Setting up responsive breakpoints using REM units
Benefits of Using PX to REM Converter
- Instant and accurate pixel to REM conversions
- Better accessibility through relative unit usage
- Simplified responsive design implementation
- Consistent scaling across your entire website
- Time-saving calculations for multiple values
Professional Tips for Using PX to REM Converter
- Use the PX to REM Converter for all font-size declarations to maintain consistency
- Convert spacing units (margin, padding) using the PX to REM Converter for better proportions
- Combine REM values from the PX to REM Converter with other relative units for flexible layouts
- Keep your root font size consistent throughout your project for predictable scaling
- Save commonly used conversions from the PX to REM Converter for quick reference
Related Tools
- REM to PX Converter — Convert REM units back to pixel values (reverse conversion)