How much is 16 px in rem?

With the default 16 px base it is exactly 1 rem.

How is rem different from em?

Em is relative to the parent font size, so it can compound in nested elements. Rem always refers to the root element.

What if I set html to 62.5%?

Then 1 rem is 10 px, which makes mental maths easier. Enter 10 as the base so the tool calculates the same way.

Does the tool round the result?

To four decimal places, which is enough for CSS.

Free online tools

px to rem converter

Enter a value in pixels or in rem and the other field updates instantly. The default base is 16 px, and you can change it.

Pixels (px)

Rem

Base (px)

Default 16, the font size of the html element.

1.5rem

Common values

px	rem
10px	0.625rem
12px	0.75rem
14px	0.875rem
16px	1rem
18px	1.125rem
20px	1.25rem
24px	1.5rem
28px	1.75rem
32px	2rem
40px	2.5rem
48px	3rem
64px	4rem

Your data never leaves your browser. Nothing is sent to a server.

How to use it

Enter a value in pixels or in rem.
If your base font size is not 16 px, change the base.
Copy the result with the rem unit.
Use the table to check typical sizes quickly.

How rem is calculated

The rem unit is relative to the font size of the root html element. With the default 16 pixels, 1 rem is 16 px, so 24 px is 1.5 rem. The formula is pixels divided by the base size.

Why rem instead of px

Sizes in rem scale with the browser font settings. Someone who raised the default text size gets a larger interface. Pixels do not do that, which is why rem is usually the better choice for text and spacing.

What not to convert to rem

Thin borders, shadows and icon details are often left in pixels because they should look the same at every text size. Use rem where the interface should grow with readability.

Frequently asked questions

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