font-weight
The font-weight
CSS property sets the weight (or boldness) of the font. The weights available depend on the font-family
that is currently set.
Try it
Syntax
css
/* Keyword values */
font-weight: normal;
font-weight: bold;
/* Keyword values relative to the parent */
font-weight: lighter;
font-weight: bolder;
/* Numeric keyword values */
font-weight: 100;
font-weight: 200;
font-weight: 300;
font-weight: 400; /* normal */
font-weight: 500;
font-weight: 600;
font-weight: 700; /* bold */
font-weight: 800;
font-weight: 900;
/* Global values */
font-weight: inherit;
font-weight: initial;
font-weight: revert;
font-weight: revert-layer;
font-weight: unset;
The font-weight
property is specified using any one of the values listed below.
Values
normal
-
Normal font weight. Same as
400
. bold
-
Bold font weight. Same as
700
. lighter
-
One relative font weight lighter than the parent element. Note that only four font weights are considered for relative weight calculation; see the Meaning of relative weights section below.
bolder
-
One relative font weight heavier than the parent element. Note that only four font weights are considered for relative weight calculation; see the Meaning of relative weights section below.
<number>
-
A
<number>
value between 1 and 1000, inclusive. Higher numbers represent weights that are bolder than (or as bold as) lower numbers. Certain commonly used values correspond to common weight names, as described in the Common weight name mapping section below.
In earlier versions of the font-weight
specification, the property accepts only keyword values and the numeric values 100, 200, 300, 400, 500, 600, 700, 800, and 900; non-variable fonts can only really make use of these set values, although fine-grained values (e.g. 451) will be translated to one of these values for non-variable fonts using the Fallback weights system.
CSS Fonts Level 4 extends the syntax to accept any number between 1 and 1000 and introduces Variable fonts, which can make use of this much finer-grained range of font weights.
Fallback weights
If the exact weight given is unavailable, then the following rule is used to determine the weight actually rendered:
- If the target weight given is between
400
and500
inclusive:- Look for available weights between the target and
500
, in ascending order. - If no match is found, look for available weights less than the target, in descending order.
- If no match is found, look for available weights greater than
500
, in ascending order.
- Look for available weights between the target and
- If a weight less than
400
is given, look for available weights less than the target, in descending order. If no match is found, look for available weights greater than the target, in ascending order. - If a weight greater than
500
is given, look for available weights greater than the target, in ascending order. If no match is found, look for available weights less than the target, in descending order.
Meaning of relative weights
When lighter
or bolder
is specified, the below chart shows how the absolute font weight of the element is determined.
Note that when using relative weights, only four font weights are considered — thin (100), normal (400), bold (700), and heavy (900). If a font-family has more weights available, they are ignored for the purposes of relative weight calculation.
Inherited value | bolder |
lighter |
---|---|---|
100 | 400 | 100 |
200 | 400 | 100 |
300 | 400 | 100 |
400 | 700 | 100 |
500 | 700 | 100 |
600 | 900 | 400 |
700 | 900 | 400 |
800 | 900 | 700 |
900 | 900 | 700 |
Common weight name mapping
The numerical values 100
to 900
roughly correspond to the following common weight names (see the OpenType specification):
Value | Common weight name |
---|---|
100 | Thin (Hairline) |
200 | Extra Light (Ultra Light) |
300 | Light |
400 | Normal (Regular) |
500 | Medium |
600 | Semi Bold (Demi Bold) |
700 | Bold |
800 | Extra Bold (Ultra Bold) |
900 | Black (Heavy) |
950 | Extra Black (Ultra Black) |
Variable fonts
Most fonts have a particular weight which corresponds to one of the numbers in Common weight name mapping. However some fonts, called variable fonts, can support a range of weights with a more or less fine granularity, and this can give the designer a much closer degree of control over the chosen weight.
For TrueType or OpenType variable fonts, the "wght" variation is used to implement varying widths.
Note: For the example below to work, you'll need a browser that supports the CSS Fonts Level 4 syntax in which font-weight
can be any number between 1
and 1000
. The demo loads with font-weight: 500;
. Change the value to see the weight of the text change.
Accessibility concerns
People experiencing low vision conditions may have difficulty reading text set with a font-weight
value of 100
(Thin/Hairline) or 200
(Extra Light), especially if the font has a low contrast color ratio.
Formal definition
Initial value | normal |
---|---|
Applies to | all elements. It also applies to ::first-letter and ::first-line . |
Inherited | yes |
Computed value | the keyword or the numerical value as specified, with bolder and lighter transformed to the real value |
Animation type | a font weight |
Formal syntax
font-weight =
<font-weight-absolute> |
bolder |
lighter
<font-weight-absolute> =
normal |
bold |
<number [1,1000]>
Examples
Setting font weights
HTML
html
<p>
Alice was beginning to get very tired of sitting by her sister on the bank,
and of having nothing to do: once or twice she had peeped into the book her
sister was reading, but it had no pictures or conversations in it, "and what
is the use of a book," thought Alice "without pictures or conversations?"
</p>
<div>
I'm heavy<br />
<span>I'm lighter</span>
</div>
CSS
css
/* Set paragraph text to be bold. */
p {
font-weight: bold;
}
/* Set div text to two steps heavier than
normal but less than a standard bold. */
div {
font-weight: 600;
}
/* Set span text to be one step lighter
than its parent. */
span {
font-weight: lighter;
}
Result
Specifications
Specification |
---|
CSS Fonts Module Level 4 # font-weight-prop |
Browser compatibility
BCD tables only load in the browser