What Units Can You Convert?
Each Convert supports PX, REM, EM, %, VW, and VH—perfect for responsive layouts and scalable typography.
Convert PX, REM, EM, %, VW & VH easily with Each Convert. Build responsive designs fast.
Each Convert supports PX, REM, EM, %, VW, and VH—perfect for responsive layouts and scalable typography.
It's free, fast, and developer-friendly. Instantly calculate CSS units for consistent design across all devices.
Absolute units such as PX, PT, MM, CM and IN always describe the same size. In CSS, 1 inch is defined as 96 px, so 1 pt = 1.333 px, 1 mm = 3.78 px and 1 cm = 37.8 px. They are predictable, which makes them good for borders, shadows and print layouts.
Relative units scale with something else: REM with the root font size (16 px by default), EM with the font size of the parent element, % with the parent's size, and VW/VH with the width and height of the browser window. They let a layout adapt to different screens and to the reader's own font-size setting.
Every converter shows the formula it uses — for example rem = px ÷ base font size and vw = px ÷ viewport width × 100 — so you can check the result or do it by hand.
New to CSS units? Read our CSS Units Complete Guide for a full breakdown of when to use each one, or check 5 Common CSS Unit Mistakes and CSS Units for Print vs. Web.
CSS units are used to determine the size of elements on a web page. They are divided into two categories: Absolute units (like PX) and Relative units (like REM, EM, VW, VH). Choosing the right unit is key to responsive web design.
The REM unit is generally considered best for font sizes because it is relative to the root font size. This allows users to scale the entire site's text by changing their browser settings, improving accessibility.
VW (Viewport Width) and VH (Viewport Height) are best used when you want an element to scale relative to the browser window size. They are great for full-screen sections, hero banners, and fluid layouts.
Yes, PX is still used for items that need fixed precision, such as borders, shadows, or specific layout details. However, for responsive spacing and typography, relative units are preferred.