px ↔ rem Converter

rem (root em) scales relative to the root font-size. If a user changes the font size in their browser, all rem values are recalculated proportionally. This improves accessibility and layout responsiveness.

The base size (usually 16px) is the font-size of the <html> element. 1rem = 1 × the base size. At 16px: 1rem = 16px, 0.5rem = 8px, 2rem = 32px. Changing the base size recalculates all rem values.

px works well for values that shouldn't scale, such as border-width (1px), small decorative elements, and shadows. px is also useful for precise positioning in pixel-perfect layouts.

rem is always relative to the root font-size (<html>). em is relative to the parent element's font-size, which can compound with nesting. rem is more predictable and is more commonly used for sizes and spacing.

Yes. Batch mode finds all px (or rem) values in CSS code and replaces them. For example, padding: 16px 24px 8px becomes padding: 1rem 1.5rem 0.5rem with a base size of 16px.