Question 1

How many px is 1 rem?

Accepted Answer

1 rem equals the root element's font size, which is typically 16px in most browsers. So 1rem = 16px by default. If the root font size is changed (e.g., html { font-size: 20px }), then 1rem = 20px.

Question 2

What is the difference between px, rem, and em?

Accepted Answer

px (pixels) is an absolute unit. rem is relative to the root element font size. em is relative to the parent element's font size. rem is preferred for responsive design because it scales consistently across the entire document.

Question 3

How do I convert px to rem?

Accepted Answer

To convert px to rem, divide the pixel value by the root font size (default 16px). For example, 24px ÷ 16 = 1.5rem. Our tool does this instantly for you.

Question 4

Is this CSS unit converter free?

Accepted Answer

Yes, completely free and runs entirely in your browser. No signup, no data upload — all calculations happen locally on your device.