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CSS Unit Converter Online - px to rem, em, vw Calculator

Free online CSS unit converter. Convert between px, rem, em, vw, vh, pt, cm, mm and more with configurable base font size.

Used for rem, em, and % calculations

UnitValue
px16
rem1
em1
vw1.5625
vh2.0833
%100
pt12
cm0.4233
mm4.2333
in0.1667

Common CSS Unit Conversions

UnitDescriptionExample
pxPixels (absolute)16px
remRoot em (relative to html font-size)1rem = 16px (default)
emRelative to parent element font-size1em = parent font-size
vwViewport width (1vw = 1% of viewport width)50vw = half screen width
vhViewport height (1vh = 1% of viewport height)100vh = full screen height
%Relative to parent element50% = half parent width
ptPoints (typography, 1pt = 1.333px)12pt
cm/mm/inPhysical units (rarely used in web)2.54cm = 1in = 96px

CSS Unit Converter

Convert between all CSS units instantly.

Features

  • All CSS units supported
  • Configurable base font
  • Viewport dimension control
  • Quick presets
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How to Use CSS Unit Converter

  1. Paste or upload your input data into the CSS Unit Converter input area
  2. Select the desired output format or conversion options
  3. Click Convert to transform your data instantly
  4. Copy the converted result or download the output file

Common Use Cases

  • Converting pixel values to rem for responsive design
  • Switching between em and px for typography
  • Calculating viewport-based units from pixel values
  • Building consistent spacing systems with unit conversions

Frequently Asked Questions

Is CSS Unit Converter free to use?
Yes, CSS Unit Converter is completely free with no signup required. You can use it as many times as you need.
Is my data safe when using CSS Unit Converter?
Absolutely. All processing happens directly in your browser. Your data is never sent to any server or stored anywhere.
What formats does CSS Unit Converter support?
CSS Unit Converter supports the formats described above. Simply paste your input data and the tool will handle the conversion automatically.
Can I convert large files?
Yes, since all processing happens in your browser, you can convert files of any reasonable size. Very large files may take a moment to process.
Will the conversion preserve my data accurately?
Yes, the conversion is lossless and preserves all data accurately. The tool handles edge cases and special characters properly.