PX to REM Converter - CSS Unit Conversion Tool

Convert pixels to rem units for responsive CSS. Set your base font size, convert single values or entire stylesheets. Files stay local.

Base Font Size:

(Usually set in html { font-size: 16px })

Pixels (px)

px → rem

REM

rem

16px ÷ 16 = 1rem

CSS with px values

CSS with rem values

Pixels	REM	Use Case

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Frequently Asked Questions

Pixels (px) are fixed units. REM units are relative to the root font size, making them better for responsive design and accessibility.

Most browsers default to 16px. This is the standard, but you can change it based on your project's root font-size setting.

REM units scale with user preferences and browser settings, improving accessibility. Users who increase their default font size will see proportionally larger text and spacing.

Yes. Paste your CSS in the 'Bulk Convert' tab and all px values will be converted to rem units.

Yes. All conversion happens in your browser using JavaScript. No data is sent to any server.

Not always. Use rem for font sizes, padding, margins. Keep px for borders (1px border should stay 1px), box-shadows, and elements that shouldn't scale with text.

Using rem makes breakpoints more flexible. If users zoom or change font size, your layout adapts proportionally rather than breaking.

rem = px ÷ base font size. With default 16px base: 24px = 24÷16 = 1.5rem. For rem to px: px = rem × base font size.

Yes. 1.5rem, 0.875rem are perfectly valid. Browsers handle decimal values well. The tool shows up to 4 decimal places for precision.

In your CSS, add: html { font-size: 18px; } or use percentages: html { font-size: 112.5%; } (which is 18px when default is 16px).

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