Question 1

What is the difference between PX and REM?

Accepted Answer

PX is an absolute unit (fixed size), while REM is relative to the root font-size of the HTML element. REM makes layouts more scalable and accessible.

Question 2

What is the default root font-size?

Accepted Answer

Most browsers default to 16px. So 1rem = 16px by default. You can change this with the html { font-size: ... } CSS rule.

Question 3

How do I calculate REM from PX?

Accepted Answer

REM = PX / root-font-size. For example, 24px with a 16px root = 24/16 = 1.5rem.

Question 4

Why should I use REM instead of PX?

Accepted Answer

REM scales with the user's browser font settings, improving accessibility. It also makes responsive design easier since changing the root font-size scales everything proportionally.

Question 5

Can I convert REM back to PX?

Accepted Answer

Yes, this tool supports both directions. Switch to REM→PX mode, enter a REM value, and get the pixel equivalent.

Question 6

What root font-size should I use?

Accepted Answer

Common choices: 16px (browser default), 10px (easy math: 1rem=10px), 14px (slightly smaller base), or 18px (larger base for readability).

Question 7

Does this tool support fractional values?

Accepted Answer

Yes, you can enter decimal values like 12.5px or 0.75rem and get precise conversions.

Question 8

Is this tool free?

Accepted Answer

Yes, completely free with no sign-up required. All calculations happen in your browser.

PX to REM Converter

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