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EM to PX Converter

Convert between em and px units for CSS. Calculate relative font sizes and spacing with em units.

Use EM to PX Converter to get instant results without uploads or sign-ups. Everything runs securely in your browser for fast, reliable output.

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About this tool

EM units are relative to parent element font size. Our EM to PX Converter helps calculate pixel equivalents for accessible, scalable CSS.

1em equals the current element's font-size. If parent is 16px, 1em = 16px, 2em = 32px, 0.5em = 8px. Useful for spacing, line-height, and responsive design.

Usage examples

Margin Based on Font Size

Spacing scales with text

margin-bottom: 1em; (equals current font size)

Larger Text

Heading relative to body

Base 16px: font-size: 2em; = 32px

How to use

  1. Enter "Base Font Size" (parent element, usually 16px).
  2. Enter value in "EM" or "Pixels".
  3. Click "Convert" to see equivalent value.
  4. Use for relative sizing in CSS.

Benefits

  • Convert em to pixels
  • Convert pixels to em
  • Relative sizing
  • Accessible typography
  • Scalable spacing
  • Responsive design

FAQs

What is an EM unit in CSS?

em is a relative unit based on parent element's font-size. 1em = current font size. If parent has font-size: 16px, then 1em = 16px, 2em = 32px, 0.5em = 8px. Cascades - if nested, multiplies: 1.5em inside 1.5em parent = 2.25em total (1.5 × 1.5).

What is the difference between em and rem?

em: relative to parent element (cascades). rem: relative to root element (html), doesn't cascade. Example: html { font-size: 16px; } → 1rem = 16px everywhere. Use rem for consistency, em for contextual scaling (line-height, padding relative to font size).

Should I use em, rem, or pixels?

Use rem: for font sizes (predictable, accessible). Use em: for padding/margin relative to current font size, line-height. Use pixels: for borders, shadows, fixed UI elements. Modern approach: rem for typography, em for spacing, px for details. Avoid cascading em issues.

What is the default font size in browsers?

Most browsers: 16px default. Users can change this in settings (accessibility). If you use rem/em, your site scales with user preferences. If you use only pixels, you ignore user settings. This is why relative units are more accessible.

How do I calculate nested em values?

Nested ems multiply. Example: parent has 1.5em (24px if base is 16px), child has 1.5em = 1.5 × 24px = 36px (or 2.25em from root). This cascading can be confusing - use rem instead to avoid compounding. em is useful when you want scaling based on parent context.

What is the 62.5% trick for rem?

Set html { font-size: 62.5%; } (62.5% of 16px = 10px). Now 1rem = 10px, making math easy: 1.2rem = 12px, 1.6rem = 16px, 2.4rem = 24px. But breaks if user changes default size. Better: keep html font-size at 100% and learn decimal conversions.

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