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
Related Calculators
You might also find these related calculators useful:
Aspect Ratio Calculator
Pixel Density Calculator