CSS Unit Converter

Convert between CSS units online for free. PX to REM, EM to PX, PT to PX, and more. Set your base font size for accurate conversions.

Runs entirely in your browser — files never uploaded

Base Font Size (px)

Value

Source Unit

rem

100

0.8333

1.4815

1rem = 16px (base font size)

1pt = 1.3333px

100% = 16px (of base)

1vw = 19.2px (assuming 1920px viewport)

1vh = 10.8px (assuming 1080px viewport)

How to use CSS Unit Converter

1. Set your base font size. Defaults to 16px, the browser standard. Adjust if your project uses a different base.
2. Enter a value. Type any number and select the source unit (px, rem, em, pt, %, vw, vh).
3. Copy results. All conversions are shown at once. Click any copy button to grab a value.

Why is the default base 16px?

Browsers use 16px as the default root font size. REM and EM calculations depend on this value.

What is the difference between rem and em?

REM is relative to the root font size. EM is relative to the parent element's font size. This tool treats both the same using the base value.

How are vw and vh calculated?

1vw = 1% of the viewport width, 1vh = 1% of the viewport height. This tool assumes a 1920x1080 viewport for conversions.