Pixels (px) are a fixed unit of measurement used in web design. They are based on the resolution of the display, meaning their size remains consistent across different devices and screen sizes. For example, an element set to 100px wide will always be 100 pixels wide, whether it’s viewed on a mobile phone or a large monitor. This makes px a great choice for elements that require precise dimensions, such as images, icons, or fixed layouts. However, since it doesn’t adapt to changes in the user’s browser settings or screen resolution, using pixels can lead to a lack of responsiveness and accessibility in some designs.
Inch (abbreviated as in) is a fixed, absolute unit of measurement commonly used in the United States and other countries that follow the imperial system. In web development and CSS, 1 inch is standardized to equal exactly 96 pixels, or 2.54 centimeters. Unlike relative units like em or rem, which depend on the font size of the parent or root elements, in always represents the same physical length regardless of the surrounding context. This makes inches useful when designing content for printing or when a specific real-world size is required on screen or paper. However, for most screen-based designs, relative units like em, rem, or percentages are preferred for better responsiveness across different devices and screen sizes.