PX to REM Converter

With a root font size of 16px (the browser default), 16px equals exactly 1rem. Half that — 8px — would be 0.5rem, and so on. You can change the root size in the calculator if your project uses a different base.

Generally yes, for font sizes and spacing. REM units respect the user's browser font size preferences, which is important for accessibility. PX is still fine for things like borders, box shadows, and small decorative details where you want pixel-precise control regardless of zoom level.

REM is always relative to the root HTML font size — consistent everywhere on the page. EM is relative to the font size of the nearest parent element which can compound if you nest elements. A 1.2em element inside another 1.2em element ends up at 1.44 times the root size. REM avoids that compounding effect entirely, which is why most developers prefer it for general-purpose sizing.

The browser default is 16px — use that unless your project explicitly sets a different root size in CSS. If you see html { font-size: 62.5% } in your stylesheet, your root is 10px (making the maths much simpler — every 10px = 1rem). If you see font-size: 100%, that's 16px. Check the root before converting.