Pixels to REM Converter

Convert PX to REM for Responsive Web Design

Our free PX to REM converter helps web developers and designers convert pixel values to rem units instantly. REM (root em) units are essential for creating accessible, responsive websites that respect user font size preferences.

Why Use REM Instead of PX?

REM units offer significant advantages over pixels for modern web development:

• Accessibility: REM units scale with the user's browser font size preferences. Users who need larger text for readability will have your entire layout scale proportionally.
• Consistency: All REM values are relative to a single root element (html), making global font size changes simple.
• Responsive Design: Changing the root font size at different breakpoints scales your entire design consistently.
• Maintainability: One change to the root font size updates your entire site's proportions.

Understanding PX vs REM

Pixels (px): Absolute units that don't scale with user preferences. 16px is always 16 pixels regardless of user settings.

REM (root em): Relative units based on the root element's font size (usually the html element). If the root is 16px, then 1rem = 16px, 2rem = 32px, etc.

The Conversion Formula

REM = Pixels ÷ Base Font Size

For example, with a 16px base font size:

• 16px ÷ 16 = 1rem
• 24px ÷ 16 = 1.5rem
• 32px ÷ 16 = 2rem

Common Base Font Sizes

CSS Implementation Example

html {
  font-size: 16px; /* This is your base */
}

/* Using REM for consistent scaling */
h1 {
  font-size: 2rem;    /* 32px */
  margin-bottom: 1rem; /* 16px */
}

p {
  font-size: 1rem;     /* 16px */
  line-height: 1.5rem; /* 24px */
}

/* Responsive scaling - change one value */
@media (max-width: 768px) {
  html {
    font-size: 14px; /* Everything scales down */
  }
}

When to Use PX vs REM

Use REM for:

• Font sizes
• Spacing (margin, padding)
• Element sizing (width, height)
• Border radius

Use PX for:

• Border widths (1px borders should stay 1px)
• Box shadows
• Media query breakpoints
• When precise pixel control is needed

Best Practices

• Set your base font size on the html element using % (62.5% = 10px, making mental math easier)
• Use REM for most sizing to ensure accessibility
• Test your design with different browser font size settings
• Combine REM with CSS clamp() for fluid typography