PX to REM Converter — Free Online Pixels to REM CSS Calculator

PX to REM Converter — Free Online Pixels to REM CSS Calculator. Free online PX to REM converter. Instantly convert pixels to REM and REM to pixels with a custom root font size — bidirectional, no upload, 100% private.

Our free px to rem converter converts pixel values to CSS REM units — and REM back to pixels — instantly, with a customizable root font size. No account, no upload, no button: just type and see the result.

How to Convert PX to REM Set your root font size (default 16px — the browser default). Enter your pixel value in the Pixels field. The REM equivalent appears instantly in the REM field. Formula: rem = px ÷ root font size . Example: 24px ÷ 16 = 1.5rem.

How to Convert REM to PX Enter a value in the REM field. The pixel equivalent updates automatically. Formula: px = rem × root font size . Example: 2rem × 16 = 32px. Why Use REM Instead of PX?

Accessibility : REM values respect the user's browser font-size preference. Fixed px does not. Scalability : Change one root value and the whole layout scales proportionally. Consistency : REM-based design tokens are easier to maintain across a design system.

Common Root Font Size Setups 16px (browser default): 1rem = 16px 10px (10px reset): 1rem = 10px — makes math easier (24px → 2.4rem) 62.5% body: same as 10px reset, 1rem = 10px Privacy All calculations run 100% locally in your browser.

Your pixel values and design tokens are never sent to any server.

Frequently asked questions

How do I convert pixels to rem?

Enter the value in the Pixels field and the REM field updates instantly with pixels divided by the Root Size. With the default 16px root, 24px becomes 1.5rem and 12px becomes 0.75rem.

How do I convert rem to px?

Type in the REM field instead, or use its arrows to step by 0.125. The Pixels field shows rem multiplied by the Root Size, so 2rem equals 32px with a 16px root.

What root font size should I use?

Use the font-size set on your html element. Browsers default to 16px, which is why the tool starts at 16. If your CSS sets the html font-size to 62.5 percent, enter 10 so that 1rem equals 10px.

What is the difference between px and rem?

A px value is a fixed CSS pixel size, while rem is relative to the font size of the root html element. Sizes in rem scale when users change their browser's default text size, which makes layouts more accessible.

How precise are the results?

REM values are rounded to 4 decimal places and pixel values to 2, which is more than enough for CSS. Changing the Root Size recalculates the REM value for the pixel value you entered.

How to use this online tool

PX to REM Converter — Free Online Pixels to REM CSS Calculator is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.

Private processing in your browser

PX to REM Converter — Free Online Pixels to REM CSS Calculator keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.

When this tool is useful

Use PX to REM Converter — Free Online Pixels to REM CSS Calculator for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.

Practical tips

Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.