CSS font-size Property
Sets the size of the font for text content
Syntax
font-size: <absolute-size> | <relative-size> | <length> | <percentage>;Values
| Value | Description |
|---|---|
| medium | Default size |
| small | Smaller than medium |
| large | Larger than medium |
| <length> | Fixed size (px, rem, em) |
| <percentage> | Relative to parent's font size |
| clamp(1rem, 2.5vw, 2rem) | Fluid responsive size |
Example
h1 {
font-size: clamp(1.75rem, 4vw, 3rem);
}
body {
font-size: 1rem;
}Understanding CSS font-size
The CSS font-size property sets the size of the font for text content. As part of the Typography module in CSS, it is one of the most commonly used properties for controlling the visual presentation of web pages.
You can set font-size to values such as medium, small, large, <length>, among others. Each value changes how the browser renders the affected element, giving you fine-grained control over your page layout and design. Choosing the right value depends on the specific design requirements of your project.
Common use cases for the font-size property include responsive web design, component-based layouts, and creating visually consistent interfaces across devices. It works closely with related properties like font, font-family, line-height to achieve complex styling effects. Understanding how these properties interact helps you write cleaner, more maintainable stylesheets.
Browser support for font-size is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. For older browsers, consider using fallback values or progressive enhancement strategies. The property can also be set dynamically via JavaScript using element.style.fontSize or the CSS custom properties (variables) approach for theming.
Related Properties
fontShorthand for font-style, font-variant, font-weight, font-stretch, font-size, line-height, and font-family
font-familySpecifies a prioritized list of font family names for the selected element
line-heightSets the amount of space between lines of text determining the height of line boxes
font-size-adjustPreserves readability of text when a fallback font is used by adjusting the x-height
Explore More CSS Properties
Browse our complete reference of 251 CSS properties with syntax, examples, and tips.