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CSS Unit Converter Online

Calculate exact conversions between CSS length units for responsive web design. Convert pixels to rem for accessibility, em for component-scoped sizing, points for print and viewport units for fluid layouts. For example, 32px becomes 2rem when the configured font size is 16px. Recheck the result whenever your project changes that font size.

Enter a value and select units

Type a numeric value, choose the source unit and target unit. The converter calculates the equivalent using standard CSS unit definitions.

Understand unit relationships

Pixels are absolute screen units. Rem and em scale relative to font sizes. Points use 72-per-inch print scaling. Viewport units are percentages of the browser viewport dimensions.

Configure root and viewport settings

Set your project root font size for accurate rem conversions and viewport width for vw and vh calculations. Default values are 16px root and 1440px viewport.

Apply to responsive design

Use this converter when building responsive layouts to ensure consistent sizing across breakpoints, font scales and component systems.

Technical references: CSS Values and Units

CSS Unit Converter FAQs

Browsers default to 16px. If your CSS sets a different html font-size, update the root field to match.
1vw equals 1% of the viewport width. 1vh equals 1% of the viewport height.
Em is relative to the parent element font size, while rem is relative to the root html font size. This converter treats both as relative to the entered root size.
At standard 96 DPI screen resolution, 1 point equals 96/72 pixels, approximately 1.333px.
Percentages depend on the parent element context and are not included. Use vw for viewport-relative percentage alternatives.
Point conversions assume standard 96 DPI screens. Print DPI may differ, so verify point values with your print output settings.
No. All calculations run locally in your browser.
Yes. Convert between px and rem to determine the correct Tailwind spacing scale values.
The converter handles single unit values. For complex calc expressions, convert each component separately.

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