line-height

The line-height CSS property sets the amount of space used for lines, such as in text. On block-level elements, it specifies the minimum height of line boxes within the element. On non-replaced inline elements, it specifies the height that is used to calculate line box height.

/* Keyword value */
line-height: normal;

/* Unitless values: use this number multiplied
by the element's font size */
line-height: 3.5;

/* <length> values */
line-height: 3em;

/* <percentage> values */
line-height: 34%;

/* Global values */
line-height: inherit;
line-height: initial;
line-height: unset;

<div class="grid">
  <div class="row">
    <div class="cell">line-height: normal
      <p class="normal">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur tristique libero ultrices luctus.</p>
    </div>
    <div class="cell">line-height: 1.2
      <p class="number">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur tristique libero ultrices luctus.</p>
    </div>
    <div class="cell">line-height: 21px
      <p class="size">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur tristique libero ultrices luctus.</p>
    </div>
    <div class="cell">line-height: 150%
      <p class="percent">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur tristique libero ultrices luctus.</p>
    </div>
  </div>
</div>

html,
body {
  height: 100%;
  box-sizing: border-box;
  background: #EEE;
}

.grid {
  width: 100%;
  height: 100%;
  display: flex;
  font: 1em monospace;
}

.row {
  display: flex;
  flex: 1 auto;
  flex-direction: row;
  flex-wrap: wrap;
}

.col {
  display: flex;
  flex: 1 auto;
  flex-direction: column;
}

.cell {
  margin: .5em;
  padding: .5em;
  background-color: #FFF;
  overflow: hidden;
  text-align: center;
  flex: 1;
  white-space: nowrap;
}

.note {
  background: #fff3d4;
  padding: 1em;
  margin: .5em;
  font: .8em sans-serif;
  text-align: left;
  flex: 1;
  white-space: nowrap;
}

p {
  font-family: sans-serif;
  background: #E4F0F5;
  padding: .5em;
  margin: .5em;
  text-align: left;
  white-space: normal;
}

.normal  { line-height: normal; }
.number  { line-height: 1.2; }
.size    { line-height: 21px; }
.percent { line-height: 150%; }

Syntax

The line-height property is specified as any one of the following:

• a <number>
• a <length>
• a <percentage>
• the keyword normal.

Values

normal

Depends on the user agent. Desktop browsers (including Firefox) use a default value of roughly 1.2, depending on the element's font-family.

<number>

The used value is this unitless <number> multiplied by the element's own font size. The computed value is the same as the specified <number>. In most cases, this is the preferred way to set line-height and avoid unexpected results due to inheritance.

<length>

The specified <length> is used in the calculation of the line box height. Values given in em units may produce unexpected results (see example below).

<percentage>

Relative to the font size of the element itself. The computed value is this <percentage> multiplied by the element's computed font size. Percentage values may produce unexpected results (see the second example below).

Formal syntax

normal | <number> | <length> | <percentage>

Examples

Basic example

/* All rules below have the same resultant line height */

div { line-height: 1.2;   font-size: 10pt; }   /* number */ 
div { line-height: 1.2em; font-size: 10pt; }   /* length */ 
div { line-height: 120%;  font-size: 10pt; }   /* percentage */
div { font: 10pt/1.2  Georgia,"Bitstream Charter",serif; } /* font shorthand */

It is often more convenient to set line-height by using the font shorthand as shown above, but this requires the font-family property to be specified as well.

Prefer unitless numbers for line-height values

This example shows why it is better to use <number> values instead of <length> values. We will use two <div> elements. The first, with the green border, uses a unitless line-height value. The second, with the red border, uses a line-height value defined in ems.

CSS

.green {
  line-height: 1.1;
  border: solid limegreen;
}

.red {
  line-height: 1.1em;
  border: solid red;
}

h1 {
  font-size: 30px;
}

.box {
  width: 18em;
  display: inline-block;
  vertical-align: top;
  font-size: 15px;
}

HTML

<div class="box green">
 <h1>Avoid unexpected results by using unitless line-height.</h1>
  length and percentage line-heights have poor inheritance behavior ...
</div>

<div class="box red">
 <h1>Avoid unexpected results by using unitless line-height.</h1>
  length and percentage line-heights have poor inheritance behavior ...
</div>

<!-- The first <h1> line-height is calculated from its own font-size   (30px × 1.1) = 33px  --> 
<!-- The second <h1> line-height results from the red div's font-size  (15px × 1.1) = 16.5px,  probably not what you want -->

Result

Specifications

Browser compatibility

See also

• font, font-size