What is a REM to PX converter?
A REM to PX converter calculates the pixel value represented by a CSS rem length. REM values are relative to the document root, so the result depends on the computed font size of the html element.
This conversion is useful when comparing CSS with a pixel-based design, reading computed browser styles, or checking how a component changes under a different root font size.
How to convert REM to PX
- Start with the default
1rem = 16pxconversion, or enter another REM value. - Keep the root font size at
16px, or change it to match your project. - Copy the pixel result.
Both fields are editable. You can paste values such as 1.5rem or 24px, select a common root-size preset, and paste the other unit to move the value to the matching field.
REM to PX formula and example
Use this formula:
PX = REM × Root Font SizeFor a 16px root font size:
1.5rem × 16px = 24pxWith a 20px root, the same 1.5rem value represents 30px.
Common REM to PX conversions
The interactive table above updates when you change the root font size and can be exported as a CSV file. These common values use a 16px root:
| REM | PX |
|---|---|
| 0.25rem | 4px |
| 0.5rem | 8px |
| 0.75rem | 12px |
| 1rem | 16px |
| 1.25rem | 20px |
| 1.5rem | 24px |
| 2rem | 32px |
| 3rem | 48px |
Why convert REM back to PX?
Design tools commonly present dimensions in pixels, while production CSS may use REM. Converting back to pixels helps compare a component with a design specification, understand computed dimensions in browser developer tools, and test the effect of different root font sizes.
PX and REM can be used together. REM is useful when a value should scale with the root font size; PX can be appropriate for fixed details such as thin borders.
How to find the root font size
Check the font-size declared for html or inspect the html element’s computed styles in browser developer tools. If the project has no custom root size, 16px is a practical starting point, but it is not guaranteed.
Need the forward calculation? Use the PX to REM Converter.
REM to PX FAQ
How do I convert REM to PX?
Multiply the REM value by the root font size. For example, 1.5 × 16 = 24px.
How many pixels is 1rem?
At a 16px root font size, 1rem equals 16px. At an 18px root, it equals 18px.
How many pixels is 1.5rem?
At a 16px root font size, 1.5rem equals 24px. At a 20px root, it equals 30px.
Is REM based on the parent font size?
No. REM is based on the root element’s font size. EM uses a local font-size context instead.
Why does the same REM value produce different PX values?
The root font size differs between projects or responsive states. Multiply the REM value by the root size used in the current state.
Can I convert negative REM values?
Yes. Negative lengths can be valid for CSS properties such as margins and transforms, so the converter preserves them.