PX to REM
Convert CSS pixels and rem values in your browser.
This runs in your browser. Nothing is uploaded.
Drop a file here or choose oneChoose file
Why convert px to rem?
CSS pixels are useful when a value should describe a precise screen-sized detail, such as a border or a small icon adjustment. The remunit is relative to the root element's font size. Spacing, type, and layout values expressed in rem can scale together when a user changes the browser's text size or when a design system changes its root scale.
A rem value is not automatically more accessible or more responsive. The right unit depends on the component, the browser behavior you want, and the rest of your CSS. Keep pixels when a fixed measurement is intentional, and use rem when a value should follow the root text scale. Check the result in the actual layout instead of converting every number mechanically.
The default base is 16px
This converter starts with a base font size of 16px because that is the common browser default for the root element. With that base, 16px becomes 1rem, 8px becomes 0.5rem, and 24px becomes 1.5rem. If your stylesheet changes html or uses a different root scale, enter that base before converting. The same base must be used when converting back from rem to px.
Results are rounded to four decimal places and trailing zeroes are removed. That keeps values such as 1rem readable while retaining enough precision for ordinary CSS spacing and typography. A rounded result is a practical representation, not a guarantee that a browser will render the same physical size on every display.
Convert values inside CSS
Paste a CSS snippet to convert every matching source unit in declarations. Comments and quoted strings are left alone, so a note such as/* 16px */ and generated content such ascontent: "16px" are not changed. Values without the selected source unit are preserved. You can copy the CSS output or download it asconverted.css.
PX to REM is a unit converter, not a design-token system. It does not infer semantic names, group repeated values, choose a spacing scale, update variables, or check whether a converted value fits your component rules. Review custom properties, calculations, media queries, and browser fallbacks in the context of your project. For formatting and indentation, use the CSS Formatter.
Private local conversion
Numbers and CSS stay in this browser. Nothing is uploaded while you enter a base, paste a snippet, convert values, copy the result, or download a file. The tool does not fetch stylesheets or inspect your project, so it cannot know whether a declaration is overridden or whether a variable is defined elsewhere. Test the converted stylesheet in your normal build and browser checks.
FAQ
Does PX to REM upload my CSS?
No. Unit conversion runs in your browser, and TheDevTab does not receive the values or CSS you enter.
What base font size does the converter use?
The default base is 16px. Change it when your root element uses another font size, and use the same base for a matching rem to px conversion.
How is px converted to rem?
The converter divides the pixel value by the base font size. With a 16px base, 16px is 1rem and 8px is 0.5rem.
How is rem converted to px?
The converter multiplies the rem value by the selected base font size. With a 16px base, 1rem is 16px.
Are comments and strings changed in CSS input?
No. Numbers inside CSS comments and quoted strings are preserved so documentation and generated content are not changed accidentally.
Does this tool create design tokens?
No. It changes matching units only. It does not infer semantic names, create variables, choose a spacing scale, or validate a stylesheet.
How precise are the conversion results?
Results are rounded to up to four decimal places and trailing zeroes are removed. Review rounded values in the target layout when exact visual dimensions matter.