1 em equals 16 pixels (px) in CSS by default.
Table of Contents
When converting 1 em to CSS pixel units, the actual size depends on the font size of the parent element or the root element. By default, most browsers set the root font size to 16px, so 1 em is equivalent to 16px unless otherwise specified.
Conversion Tool
Result in css:
Conversion Formula
The formula to convert em units to CSS pixels is:
pixels = em × base font size
Where the base font size is the font size of the parent or root element, often 16px by default in browsers.
This works because an “em” unit in CSS is relative to the computed font size of its container. So if the font size is 16px, 1em equals 16px, 2em equals 32px, and so on.
Example calculation:
- Given 1 em, and default base font size 16px
- Calculate: 1 × 16 = 16 pixels
- Therefore, 1 em = 16px
Conversion Example
- 2.5 em to pixels:
- Assuming base font size is 16px.
- Calculate 2.5 × 16 = 40 pixels.
- So 2.5 em equals 40px.
- 0.75 em to pixels:
- Base font size 16px.
- Calculate 0.75 × 16 = 12 pixels.
- Therefore, 0.75 em equals 12px.
- 3 em to pixels:
- Base font size 16px.
- Calculate 3 × 16 = 48 pixels.
- Thus, 3 em equals 48px.
- 1.2 em to pixels:
- Base font size 16px.
- Calculate 1.2 × 16 = 19.2 pixels.
- Hence, 1.2 em equals 19.2px.
- 0.5 em to pixels:
- Base font size 16px.
- Calculate 0.5 × 16 = 8 pixels.
- So, 0.5 em equals 8px.
Conversion Chart
| em | Pixels (px) |
|---|---|
| -24.0 | -384.0 |
| -20.0 | -320.0 |
| -16.0 | -256.0 |
| -12.0 | -192.0 |
| -8.0 | -128.0 |
| -4.0 | -64.0 |
| 0.0 | 0.0 |
| 4.0 | 64.0 |
| 8.0 | 128.0 |
| 12.0 | 192.0 |
| 16.0 | 256.0 |
| 20.0 | 320.0 |
| 24.0 | 384.0 |
| 26.0 | 416.0 |
This chart shows the equivalent pixel values for em units from -24.0 up to 26.0. To use the chart, find the em value in the left column, then look right to see the converted pixel size assuming a 16px base font size.
Related Conversion Questions
- How many pixels does 1 em represent in CSS?
- What is the CSS pixel equivalent of 1em with default browser settings?
- How to convert 1 em to px in CSS stylesheets?
- Does 1 em always equal 16 pixels in CSS?
- Can 1 em have different pixel values depending on context?
- How do I calculate CSS pixels from an em value of 1?
- Why does 1 em sometimes result in different pixel sizes in CSS?
Conversion Definitions
em: An em is a relative unit in CSS that measures size based on the font size of the parent element. It scales proportionally, so 1 em equals the current font size, making it useful for responsive layouts and font sizing relative to surrounding content.
css: CSS (Cascading Style Sheets) is a stylesheet language used to describe the presentation of HTML documents. It controls layout, colors, fonts, and spacing by applying rules to elements, allowing developers to separate design from content for web pages.
Conversion FAQs
Why does 1 em sometimes not equal 16 pixels?
Because the em unit depends on the font size of its parent element, if the parent font size changes from the default 16px, then 1 em adapts to that size. For example, if a container sets font size to 20px, then 1 em inside it equals 20 pixels, not 16.
Can negative em values be used in CSS and what happens?
Negative em values are allowed in CSS but can cause unexpected layout issues. For example, negative margins or positioning with em units will offset elements relative to the font size, but using negative font sizes is invalid. Care must be take when using negative em values.
Is em the same as rem in CSS?
Em and rem are similar but different units. Em is relative to the font size of the element’s parent, while rem is relative to the root element’s font size (usually the html element). This makes rem consistent throughout the page, independent of nesting.
How does changing the base font size affect em conversions?
Changing the base font size adjusts all em-based sizes proportionally. If the root font size is increased, 1 em becomes larger in pixels; if decreased, 1 em becomes smaller. This allows flexible scaling of UI elements on different devices or user preferences.
Why use em units instead of fixed pixels in CSS?
Em units provide scalability and responsiveness, letting elements adapt to user settings or parent container sizes. Fixed pixels can cause layout problems on different screen sizes or zoom levels, but em units create flexible, accessible designs that scale naturally.