How do I convert px to rem?

Divide the pixel value by the root font size. With the default 16px root, 24px ÷ 16 = 1.5rem. The converter does this for you.

What is the default root font size?

Browsers default the root (html) font size to 16px unless you override it, so 1rem equals 16px in a fresh stylesheet.

What is the difference between rem and em?

A rem is always relative to the root (html) font size, so it is predictable everywhere. An em is relative to the parent element's font size and compounds through nesting. Rem is usually safer for consistent sizing.

Why use rem for accessibility?

Because rem is tied to the root font size, sizing in rem scales with the user's browser font-size preference. People who increase their default font size get a proportionally larger layout, which fixed pixels would ignore.

How do I convert rem back to px?

Multiply the rem value by the root font size. With a 16px root, 1.5rem × 16 = 24px.

What if my root font size is not 16px?

Set the root font size field to your actual value. If the html element is 10px (a common "62.5%" trick), then 24px ÷ 10 = 2.4rem.

Is anything uploaded?

No — the conversion runs entirely in your browser and nothing is sent anywhere.

PX to REM Converter — Gera Tools

Convert px to rem

The rem unit is relative to the root (html) element’s font size, so sizing typography and spacing in rem keeps your layout scalable and respects the user’s browser font-size preference for accessibility. This converter turns a pixel value into the equivalent rem for a given root size, helping you migrate a design from fixed pixels to relative units.

How it works

The conversion divides the pixel value by the root font size:

rem = px ÷ root font size (px)
px  = rem × root font size (px)

Unlike em, the divisor is always the root font size, so rem values do not compound through nesting. The default root of 16px matches the browser’s standard.

Example

Convert 24px with the default 16px root:

24 ÷ 16 = 1.5rem

If the root were set to 10px (the “62.5%” technique), the same 24px would be 24 ÷ 10 = 2.4rem.

Pixels	Root	Result
24px	16px	1.5rem
8px	16px	0.5rem
24px	10px	2.4rem

Enter your numbers and the result updates instantly, all in your browser.