Em=parent font size, rem=root (16px default). Rem is more predictable.

Divide px by parent font size. 24px/16=1.5em.

16px in all browsers. 1em=1rem=16px.

1vw=1% viewport width, 1vh=1% height. For responsive layouts.

Pixel to EM Converter

Convert between CSS units: px, em, rem, pt, vw, and vh. Adjust base font size and viewport dimensions for accurate conversions.

Base Font Size (px)

Viewport Width (px)

Viewport Height (px)

Value

From Unit

Understanding CSS Units: px, em, rem, pt, vw, vh

CSS offers several unit types. Pixels (px) are absolute. Points (pt) are from print (1pt=1/72 inch=~1.333px).

Em and rem scale with font size for accessibility. Em uses parent; rem uses root html (default 16px).

Viewport units (vw, vh) are relative to browser window. 1vw=1% width. Great for responsive layouts from 320px phones to ultrawide monitors.