CSS Unit Converter: Convert CSS Length Units Online
CSS Unit Converter changes CSS length values between supported units, from px and rem to viewport and physical units. Set the root font size, parent font size, viewport, and DPI context so relative and physical values can be resolved for your use case. Convert one value, view its equivalent representations, or use “convert all in CSS” to rewrite lengths in a pasted stylesheet to one target unit.
CSS Unit Converter is a browser-based CSS Unit Converter for changing CSS length values between supported units. It handles units such as px, rem, em, pt, pc, in, cm, mm, Q, vw, vh, vmin, vmax, %, ch, and ex. Convert one value at a time or use “convert all in CSS” to rewrite the lengths in a pasted stylesheet to a target unit.
The conversion uses a configurable context: root font size, parent font size, viewport, and DPI. These settings matter because CSS units do not all resolve in the same way. For example, rem and em depend on font-size context, viewport units relate to viewport dimensions, and physical units use DPI context. Set the relevant values before converting when you need the result to reflect a particular context.
CSS length units express sizes and distances in different ways. Units such as px, pt, cm, and in provide different representations of a length, while units such as rem, em, vw, and vh depend on a font or viewport context. Converting between them can make values easier to compare, reuse, or adapt when a stylesheet or another tool expects a particular unit.
The CSS Unit Converter runs entirely in your browser. Your input is processed on your device and is not sent to a server; once the page has loaded, the tool works offline without a server dependency. This makes it useful when you want to convert CSS values without uploading your stylesheet.
The tool is designed for developers and DevOps engineers who need to inspect, compare, or rewrite CSS lengths. Whether you are checking a single value or updating lengths across a pasted stylesheet, the configurable context and unit conversion help you get a representation that suits your task.
Step 1: Enter or paste a CSS length value, or paste a stylesheet if you want to convert its lengths together.
Step 2: Choose the source and target units for a single-value conversion.
Step 3: Set the relevant context, such as root font size, parent font size, viewport, or DPI, to resolve units that depend on those values.
Step 4: For a stylesheet, switch to “convert all in CSS” mode and choose the target unit for its CSS lengths.
Step 5: Review the converted representation and copy the value or stylesheet you need.
Use case: Convert a CSS length into the unit another tool or system expects, rather than recalculating it by hand.
Use case: Check a CSS value by viewing its equivalents in supported units or bases at once.
Use case: Rewrite the lengths in a pasted stylesheet to one target unit when you need a consistent representation.
Use case: Compare a rem or em value with other units by setting the root or parent font size used for the conversion.
Use case: Resolve viewport-based lengths using viewport context when checking how a CSS value relates to a particular viewport.
Use case: Convert physical CSS lengths such as cm or in using the DPI context relevant to your calculation.