If this tool helped you, you can buy us a coffee ☕
Convert pixel values to percentages based on root font size. Ideal for CSS responsive design and fluid layouts.
PX to REM Converter
A bidirectional PX to REM converter for front-end developers and designers, featuring customizable root font sizes.
PX to EM Converter
A pixel and EM unit converter for front-end developers featuring custom base font sizes and real-time two-way conversion.
Random Password Generator
Customize character types and length to generate strong random passwords and secure your accounts.
PX to PT Converter
A pixel (PX) to point (PT) unit conversion tool for designers and developers. Supports custom PPI for typography and layout adaptation.
PX to REM Converter
A bidirectional PX to REM converter for front-end developers and designers, featuring customizable root font sizes.
PX to EM Converter
A pixel and EM unit converter for front-end developers featuring custom base font sizes and real-time two-way conversion.
Random Password Generator
Customize character types and length to generate strong random passwords and secure your accounts.
PX to PT Converter
A pixel (PX) to point (PT) unit conversion tool for designers and developers. Supports custom PPI for typography and layout adaptation.
Online JWT Parser & Decoder
Parse JWT headers, payloads, and key information online. No installation required—just paste and decode.
In responsive web development, designers and front-end engineers frequently need to convert fixed pixel (PX) dimensions from design drafts into relative percentage (%) units. This ensures elements scale dynamically based on the viewport or parent container. Our tool solves this pain point by instantly calculating the corresponding percentage value from your input pixels based on a specified root font-size, following the basic principles of CSS relative units. A pixel (PX) is an absolute length unit, whereas a percentage (%) is a relative unit based on its containing block or root element. The core calculation of this tool follows the formula: Percentage = (Pixel Value ÷ Root Font Size) × 100%. For example, with a root font size of 16px, converting 8px results in 50%.
Q: How do I convert 24px to a percentage?
A: 150%. Assuming a root font size of 16px, using the formula (24 ÷ 16) × 100% = 150%.
Q: How do I use the converted percentage value in CSS?
A: The converted result can be used directly as a CSS property value, such as width: 150%; or font-size: 87.5%;. It represents the percentage of that property value relative to its parent element or root element (for properties like font-size). In fluid layouts, using this in combination with a root font size (rem) strategy enables globally controllable responsive scaling.
Please note: The root font size and pixel values entered must be valid numbers (decimals are supported). The percentage result is relative to the root font size you set, so ensure it matches your project's actual CSS baseline. This conversion applies to CSS properties that accept percentage values (such as width, height, padding, margin, font-size, etc.), but pay attention to the specific context of the element's containing block. This tool performs pure front-end calculations and does not upload any data, ensuring your privacy and security.
For modern responsive development, we recommend adopting a fluid layout strategy using "Root Font Size + rem/percentage". For example, setting html { font-size: 62.5%; } makes 1rem = 10px (assuming the browser default is 16px), which greatly simplifies the conversion from design draft pixels to CSS rem/percentages. A typical scenario: if a button width in the design draft is 120px and the root font size is 16px, the converted percentage is (120 / 16) * 100% = 750%. If using the 62.5% baseline (where 1rem = 10px), 120px can also be written directly as 12rem. The conversion results from this tool help you quickly verify and switch between different baseline strategies.
