CSS Unit Converter

What CSS Unit Converter does

CSS Unit Converter translates values between px, rem, em, and pt with configurable base sizes. It is useful when moving a design token into CSS, checking typography scales, converting a legacy stylesheet, comparing print-oriented point values, or deciding whether a component should use root-relative or element-relative sizing. Enter a source value, choose its unit, set the root and element font sizes, and the equivalent values update immediately. The converter treats rem as relative to the root font size and em as relative to the current element font size.

Pixel and point conversion uses the CSS relationship where one point is one and one third pixels, so one pixel equals 0.75 points. Showing every equivalent at once makes it easier to spot whether a spacing or font size token is consistent with the rest of a scale. The copy button creates a compact multi-line summary for notes, pull requests, or token reviews.

Private browser-based workflow

All processing happens inside your browser with client-side JavaScript. The tool does not upload snippets, configuration values, generated data, query text, or copied examples to a server, and it does not require an account. That local-only model matters for developer utilities because the content pasted into them often looks like real application data: API responses, logs, environment-shaped samples, database queries, markup from drafts, or values copied from production debugging sessions. Keeping the transformation local reduces risk and keeps the interaction fast because there is no network round trip.

The interface is intentionally compact so you can paste input, adjust options, inspect output, copy it, and move back to your editor. Results should still be reviewed before being committed, shared publicly, or used in a production workflow. Browser tools are excellent for quick inspection and preparation, but they cannot understand every project convention, data classification rule, or application-specific validation requirement.

Practical tips

Use rem for values that should follow the document root, such as accessible font sizes and layout spacing tied to user preferences. Use em when a value should scale with the component's own font size, such as icon alignment, local padding, or nested typography. Use px carefully for exact borders, raster assets, and cases where relative scaling is not desired. Real computed sizes can be affected by browser settings, inheritance, zoom, media queries, and container-specific styles, so verify important values in developer tools.