What is PX to REM Calculator?
PX to REM calculator is a tool that converts pixel (px) values to rem units, which are relative to the root element's font size in CSS. This conversion is essential for creating responsive and accessible web designs that scale properly across different screen sizes and user preferences.
When to Use PX to REM Calculator
You should use a PX to REM calculator in the following situations:
- When developing responsive websites that need to scale proportionally across different devices
- When creating accessible designs that respect user font size preferences
- When converting an existing design from absolute units (pixels) to relative units (rems) for better maintainability
How to Calculate PX to REM
The formula to convert pixels to rems is:
rem = px ÷ root font size
Where:
- rem is the resulting value in rem units
- px is the pixel value you want to convert
- root font size is the base font size of the root element (typically 16px in most browsers)
Examples
Example 1: Converting a heading size from pixels to rems
Convert a heading size of 24px to rems with the default root font size of 16px.
| Input | Calculation | Result |
|---|---|---|
| Pixel Value: 24px Root Font Size: 16px |
24 ÷ 16 | 1.5rem |
Example 2: Converting a margin value with custom root font size
Convert a margin of 40px to rems with a custom root font size of 20px.
| Input | Calculation | Result |
|---|---|---|
| Pixel Value: 40px Root Font Size: 20px |
40 ÷ 20 | 2rem |
Example 3: Converting a small padding value
Convert a padding of 8px to rems with the default root font size of 16px.
| Input | Calculation | Result |
|---|---|---|
| Pixel Value: 8px Root Font Size: 16px |
8 ÷ 16 | 0.5rem |
Common Pixel to REM Conversions
Here's a reference table of commonly used pixel values converted to rems (based on the standard 16px root font size):
| Pixels | REMs |
|---|---|
| 4 px | 0.25 rem |
| 8 px | 0.5 rem |
| 12 px | 0.75 rem |
| 14 px | 0.88 rem |
| 15 px | 0.94 rem |
| 16 px | 1 rem |
| 18 px | 1.12 rem |
| 20 px | 1.25 rem |
| 24 px | 1.5 rem |
| 25 px | 1.56 rem |
| 32 px | 2 rem |
| 40 px | 2.5 rem |
| 48 px | 3 rem |
| 56 px | 3.5 rem |
| 64 px | 4 rem |
| 80 px | 5 rem |
| 300 px | 18.75 rem |
Benefits of Using REMs Over Pixels
Using rem units in your CSS provides several advantages:
- Better accessibility, as rem units scale with user's browser font size settings
- Easier responsiveness by simply changing the root font size in media queries
- More consistent scaling across all elements
- Improved maintainability through proportional relationships between elements
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