Increase or decrease the size of a font with CSS

The font-size property in CSS controls the size of text elements. You can use various units and keywords to set font sizes, from absolute values like pixels to relative keywords like "small" and "large".

Syntax

font-size: value;

Available Values

The font-size property accepts several types of values:

  • Absolute keywords: xx-small, x-small, small, medium, large, x-large, xx-large
  • Relative keywords: smaller, larger
  • Length units: pixels (px), points (pt), ems (em), rems (rem)
  • Percentage: relative to parent element's font size

Example: Different Font Sizes

<!DOCTYPE html>
<html>
<head>
   <title>Font Size Examples</title>
</head>
<body>
   <p style="font-size: 12px;">This font size is 12 pixels</p>
   <p style="font-size: 18px;">This font size is 18 pixels</p>
   <p style="font-size: small;">This font size is small</p>
   <p style="font-size: medium;">This font size is medium</p>
   <p style="font-size: large;">This font size is large</p>
   <p style="font-size: x-large;">This font size is extra large</p>
   <p style="font-size: 150%;">This font size is 150% of parent</p>
</body>
</html>

Example: Using CSS Classes

<!DOCTYPE html>
<html>
<head>
   <style>
      .small-text { font-size: 14px; }
      .medium-text { font-size: 18px; }
      .large-text { font-size: 24px; }
      .responsive-text { font-size: 2em; }
   </style>
</head>
<body>
   <p class="small-text">Small text using CSS class</p>
   <p class="medium-text">Medium text using CSS class</p>
   <p class="large-text">Large text using CSS class</p>
   <p class="responsive-text">Responsive text using em units</p>
</body>
</html>

Comparison of Units

Unit Description Best Use Case
px (pixels) Absolute unit Fixed layouts
em Relative to parent font size Component-based scaling
rem Relative to root font size Consistent scaling
% Percentage of parent Proportional sizing

Conclusion

The font-size property offers flexible options for controlling text size. Use pixels for precise control, em/rem for responsive designs, and keywords for quick styling. Choose the unit that best fits your layout requirements.

Updated on: 2026-03-15T23:18:59+05:30

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