What is 1em in pixels?

By default (16px base), 1em equals 16px. If the base font size is different — for example, the parent element sets font-size: 20px — then 1em equals 20px. The formula is: px = em × base font size.

What base font size should I use?

Browsers default to 16px unless overridden. If your root or parent element sets a different font size, use that value. For body { font-size: 18px }, use 18 as your base.

How is em different from rem?

em is relative to the nearest parent element font size; rem is always relative to the root element (html) font size. Both convert to pixels using the same formula, just with different base values.

Why does the result have decimal places?

Pixel values computed from em can be fractional. Browsers typically sub-pixel-render these. The tool shows up to 4 decimal places for precision; round to 0 for whole-pixel estimates.

Em to Pixel Converter

Name: Em to Pixel Converter
Availability: InStock
Author: Nham Vu

Convert em units to pixels (and back) using a configurable base font size. Default base is 16px.

Base Font Size (px)

px — browser default is 16

Em to Pixels

Em value

Pixel result

Pixels to Em

Pixel value

Em result

Common Em Values Reference

Em	Pixels (base 16px)	Common use

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Summary

Convert em units to pixels (and back) using a configurable base font size. Default base is 16px.

How it works

Enter an em value in the Em to Px panel.
Set the base font size (default 16px — the browser default).
The pixel result is calculated as: px = em × base font size.
Use the Px to Em panel for the reverse: em = px / base font size.
The reference table shows common em values at the current base font size.

Use cases

Convert a design spec given in em to pixels for QA comparison.
Check what pixel size a CSS em value renders at a custom base font.
Quickly look up common em values (0.5em, 1em, 1.5em, 2em) in pixels.
Verify responsive typography scales across different base font sizes.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu