PX to REM converter

Convert using your root font size.

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PX to REM converter processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Your input

Direction

Options and local file

Root font size in pixels

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Optional settings apply only to this tab.

Your result

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

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Updated 2026-09-20

PX to REM converter explained

Divide a pixel length by the document’s root font size to get rem, or multiply rem by that root size to get pixels. Enter the root size used by your stylesheet rather than assuming every site uses the same one.

Next: JSON formatter

A worked example

At a root font size of 16px, 24px is 1.5rem. If the root font size changes to 20px, the same 24px is 1.2rem.

Before you use the result

This is CSS length arithmetic, not physical screen measurement. Browser zoom and device pixel density do not change the formula. Output rounds to eight decimal places.

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ToolOctopus. “PX to REM converter.” Updated 2026-09-20. https://tooloctopus.com/px-to-rem-converter.

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