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PX to REM Converter

Convert pixels to rem units and vice versa with custom base font size, batch conversion, and reference table.

Base Font Size (px)

Pixels (px)

→

REM

Formula: rem = px ÷ 16

About PX to REM Converter

Free online PX to REM converter for frontend developers and designers. Enter a pixel value and instantly get the rem equivalent (or convert rem back to pixels). Customize the base font size (default 16px), use batch mode to convert multiple values at once, or check the built-in reference table for common px-to-rem conversions. Essential for responsive CSS development and accessibility. 100% browser-based, no signup required.

Frequently Asked Questions

What is 1rem in pixels?▾

By default, 1rem equals 16px because browsers set the root font size to 16px. If you change the root font size (html { font-size: 20px; }), then 1rem equals 20px. This tool lets you set any base font size for accurate conversion.

Why use rem instead of px?▾

Rem units are relative to the root font size, making your layouts more accessible and scalable. When users change their browser's default font size (for accessibility), rem-based layouts adjust automatically while px-based layouts don't. Rem is the recommended unit for font sizes, padding, and margins in modern CSS.

What is the difference between rem and em?▾

Rem is relative to the root (html) font size, while em is relative to the parent element's font size. Rem is more predictable because it always refers to one fixed value. Em can compound — a 2em inside another 2em becomes 4x the root size. Use rem for consistency and em when you intentionally want relative sizing.

Can I convert multiple values at once?▾

Yes. Switch to 'Batch' mode and enter multiple values separated by commas or line breaks. The tool converts them all instantly and lets you copy the results.

What base font size should I use?▾

The default browser font size is 16px, and most websites keep this as the root size. If your CSS sets html { font-size: 62.5%; } (a popular trick to make 1rem = 10px), enter 10 as the base. Always match this tool's base to your project's actual root font size.

Is this tool free?▾

Yes, completely free with no signup required. All conversions happen in your browser — nothing is sent to any server.

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