PX to Percent Converter
Convert pixel values to percentage. Set the parent element's size to get accurate conversion.
PX to % Conversion Table
Complete reference: pixels 1–100 converted to percent.
| px | % |
|---|
How to Convert PX to Percent
Percentage in CSS is relative to the parent element's value for the same property. For font-size, the formula is:
% = (px ÷ parent-font-size) × 100With a parent font-size of 16px, 16px = 100%, 24px = 150%, and 12px = 75%. For width, replace "parent-font-size" with the parent element's width. The context changes depending on which CSS property uses the percentage.
This converter focuses on font-size conversion, where 100% equals the parent element's font-size. Adjust the parent font-size setting above to match your specific context.
When to Use Percentage Units
Percentage is one of the most versatile CSS units:
- Fluid layouts: Setting
width: 50%makes an element take half its parent's width, creating naturally responsive layouts without media queries. - Font-size inheritance:
font-size: 87.5%(14px at default base) scales relative to the parent, similar to em units. In fact,font-size: 150%is identical tofont-size: 1.5em. - Responsive images:
max-width: 100%is the standard technique for making images fit their container without overflowing. - Grid systems: Traditional CSS grid systems (like Bootstrap's) use percentages for column widths: 8.333% per column in a 12-column grid.
- Vertical padding trick: Padding-top or padding-bottom as a percentage is relative to the element's width (not height), enabling aspect-ratio boxes:
padding-top: 56.25%creates a 16:9 ratio container.
Percentage vs EM vs REM
For font-size, percentage and em are functionally identical: font-size: 150% equals font-size: 1.5em. Both reference the parent element's font size and both compound when nested.
REM avoids compounding by always referencing the root. For most modern CSS, rem is preferred for font sizes and spacing, while percentage is preferred for widths and layout dimensions.
/* Common percentage patterns */
.container { width: 90%; max-width: 1200px; margin: 0 auto; }
.half { width: 50%; }
.third { width: 33.333%; }
img { max-width: 100%; height: auto; }Frequently Asked Questions
What does 100% equal in CSS?
It depends on the property. For font-size, 100% equals the parent element's font-size. For width, 100% equals the parent element's content width. For padding-top, 100% equals the element's own width. Context matters.
Is font-size: 100% the same as font-size: 1em?
Yes, for font-size they are functionally identical. Both reference the parent element's font-size. The difference is purely a matter of notation preference.
How do I convert px to % for width?
Divide the element's desired pixel width by the parent element's pixel width, then multiply by 100. For example, a 300px element inside a 1200px container = (300 ÷ 1200) × 100 = 25%.