CSS font-weight

The CSS font-weight property is used for specifying the weight of the font. You can specify a font as being bold, or another relevant value.

Although the font-weight property is typically used for specifying bold text, it can also be used for specifying a particular weight of a font face. Many typefaces come in a range of weights. You can specify that the body text is displayed in a light typeface, such as 300, and article ledes are displayed in say, 500. This assumes that such weights are available for the particular font face being used.

When a weight is specified for which no face exists, a face with a nearby weight is used. In general, bold weights map to faces with heavier weights and light weights map to faces with lighter weights.

If a bold font has been specified for which there is no bold face, the user agent will usually synthesize the effect. This can be disabled with the font-synthesis property.

Tip: Use font to set the most common font properties in one go.

Syntax

font-weight: normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900

Possible Values

normal
Same as 400.
bold
Same as 700.
bolder
Specifies a bolder weight than the inherited value.
lighter
Specifies a lighter weight than the inherited value.
100
Thin.
200
Extra Light (Ultra Light).
300
Light.
400
Normal.
500
Medium.
600
Semi Bold (Demi Bold).
700
Bold.
800
Extra Bold (Ultra Bold).
900
Black (Heavy).

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial
Represents the value specified as the property's initial value.
inherit
Represents the computed value of the property on the element's parent.
unset
This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

General Information

Initial Value
normal
Applies To
All elements
Inherited?
Yes
Media
Visual
Animatable
Yes (see example)

Example Code

p {
  font-weight: 300;
  }
strong {
  font-weight: bolder;
}

Official Specifications