Easily convert EM to REM with our online EM to REM converter. Simplify your responsive design workflow and ensure consistent CSS units across your site.
EM to REM Manual Table Conversion
We’re assuming the standard default browser font-size of 16px.
| EM | REM |
| 0.01em | 0.01rem |
| 0.03em | 0.03rem |
| 0.05em | 0.05rem |
| 0.08em | 0.08rem |
| 0.1em | 0.1rem |
| 0.15em | 0.15rem |
| 0.2em | 0.2rem |
| 0.5em | 0.5rem |
| 1em | 1rem |
| 2em | 2rem |
| 3em | 3rem |
| 4em | 4rem |
| 5em | 5rem |
| 6em | 6rem |
| 8em | 8rem |
| 10em | 10rem |
| 15em | 15rem |
| 20em | 20rem |
| 30em | 30rem |
| 40em | 40rem |
| 50em | 50rem |
| 60em | 60rem |
| 80em | 80rem |
| 100em | 100rem |
REM to EM
| REM | EM |
| 0.01rem | 0.01em |
| 0.03rem | 0.03em |
| 0.05rem | 0.05em |
| 0.08rem | 0.08em |
| 0.1rem | 0.1em |
| 0.15rem | 0.15em |
| 0.2rem | 0.2em |
| 0.5rem | 0.5em |
| 1rem | 1em |
| 2rem | 2em |
| 3rem | 3em |
| 4rem | 4em |
| 5rem | 5em |
| 6rem | 6em |
| 8rem | 8em |
| 10rem | 10em |
| 15rem | 15em |
| 20rem | 20em |
| 30rem | 30em |
| 40rem | 40em |
| 50rem | 50em |
| 60rem | 60em |
| 80rem | 80em |
| 100rem | 100em |
What is EM in CSS?
EM is a CSS unit of measurement that is relative to the font size of the current element or its parent element. Like REM, it is used to create flexible, scalable layouts, but with one key difference: while REM is relative to the root element’s font size, EM is relative to the font size of the element it’s applied to (or the nearest parent element).
Here’s how EM works:
- EM: This unit is relative to the font size of the element or its parent element. For instance, if a parent element has a font size of 16px, then
1emequals 16px. However, if the font size of a parent or containing element changes, the EM values inside it adjust proportionally, which can sometimes result in compounding or cascading size effects.
Example:
- If the parent element has a font size of 16px and you set a child element to
2em, the child element’s font size will be 32px (2 * 16px). - If the parent element has a font size of 16px, but you apply
2emto the parent and2emto the child, the child’s font size will be 64px (because it multiplies by the parent’s new size).
Advantages of EM:
- Relative to Parent: It provides flexibility in nested contexts where you want elements to scale based on the size of their parent element.
- Versatile: It is often used for sizing elements like padding, margins, and font sizes where flexibility is needed.
Potential Downsides:
- Cascading Effects: The size of elements can quickly become difficult to manage because they depend on their parent elements, leading to larger-than-expected values if the EM units are applied multiple times in a hierarchy.
- Less Predictability: Compared to REM, which remains consistent across a page, EM units can change in unpredictable ways, especially in nested structures.
Difference Between EM and REM:
- EM is relative to the font size of the parent element or the element itself.
- REM is always relative to the root element’s font size, making it more predictable and easier to manage for larger projects, especially in responsive design.
In summary, while EM is great for situations where you want an element to scale with its parent, it requires more attention in complex layouts to avoid unintentional size increases.
What is REM in CSS?
REM (Root Em) is a CSS unit of measurement that is relative to the root element (<html>) font size. It is commonly used in web design to create scalable and flexible layouts, ensuring that elements adjust proportionally based on the user’s settings or device preferences.
Here’s how REM works:
- REM: This unit is relative to the font size of the root element (usually the
<html>tag). For example, if the font size of the root element is set to 16px, then1remequals 16px. If you use2rem, it would be equal to 32px.
Using REM units provides consistent scaling across elements, especially when compared to absolute units like pixels (px). This is particularly useful for responsive design, where flexibility and adaptability to different screen sizes or user preferences are important.
Some key advantages of using REM:
- Consistency: REM ensures that scaling is consistent across the entire site because it references the root font size.
- Accessibility: It allows users to adjust font sizes based on their browser settings, making the website more accessible.
- Responsive Design: It works well with media queries and helps ensure that websites look good across different devices.
The difference between REM and EM:
- EM: EM is relative to the font size of the parent element, not the root element. This can sometimes lead to cascading size changes, making EM less predictable in complex layouts.
REM tends to be preferred for its simplicity and ease of control when designing responsive and accessible websites.
EM vs REM
| Aspect | EM | REM |
|---|---|---|
| Meaning | EM is relative to the font size of the parent element. | REM is relative to the root element’s font size (typically <html>). |
| Reference Point | Based on the size of the parent element. | Based on the root element’s font size (usually 16px). |
| Inheritance | Inherited and compounded based on parent element’s size, which can cause unintended growth when nested. | Not compounded—always relative to the root size, even when nested. |
| Consistency | Can vary and lead to inconsistent sizes due to inheritance from parent elements. | Provides consistency, as it remains relative to the root element’s size. |
| Use Cases | Useful for local adjustments where scaling should be relative to the parent element, such as padding or margin adjustments. | Ideal for global consistency in typography, layout, and responsive designs. |
| Responsiveness | Can be challenging to manage in responsive designs as sizes change with parent element scaling. | Easier to manage in responsive designs, as it only changes with the root element’s size. |
| Scaling Behavior | Nested elements can lead to compounding and unintentional size increases. | Scales uniformly across the site with changes in the root size, ensuring predictable behavior. |
| Common Applications | Suitable for creating flexible spaces relative to the immediate parent element. | Preferred for consistent font sizes and layouts that need to scale predictably. |
| Calculation Example | font-size: 1.5em; /* 1.5 times the size of the parent element's font size */ | font-size: 1.5rem; /* 1.5 times the root element’s font size (16px default) */ |
| Best Used For | Localized changes in element size relative to its parent, such as within specific components or widgets. | Global adjustments in layout, fonts, or spacing, making it easier to achieve uniformity and responsiveness across a site. |
Use Cases of EM and REM
Both REM and EM units in CSS have specific use cases that make them valuable for different scenarios in web design. Here’s an overview of when and why to use each:
Use Cases for REM:
REM units are particularly useful when you want consistent scaling across the entire webpage, as they always relate to the root font size (typically set on the <html> element).
Global Font Sizing:
- If you want to ensure consistent font sizing across different elements and maintain responsiveness, REM is ideal.
- For example, setting the body or root font size in pixels (e.g.,
16px) and using REM for headings, paragraphs, and other text allows uniform scaling across the entire page.
Example:
html { font-size: 16px; }
h1 { font-size: 2rem; } /* This equals 32px (2 * 16px) */
p { font-size: 1rem; } /* This equals 16px */Responsive Design:
- REM is beneficial in creating responsive layouts. Since all elements scale according to the root font size, you can easily adjust the entire design by changing the root size in a media query.
- This is useful when designing for different screen sizes, such as mobile or desktop.
Example:
@media (max-width: 768px) {
html { font-size: 14px; } /* Adjusts all sizes based on the new root size */
}Accessibility and User Preferences:
- REM supports accessibility by allowing users to adjust font sizes via browser settings. Since REM units scale according to the root element, changes in user preferences (such as increasing the default font size) will scale the entire design proportionally.
Consistent Spacing and Layout Elements:
- REM is often used for padding, margins, and other spacing-related properties to ensure consistency in layout, as everything scales from a single reference point (the root font size).
Example:
.container {
padding: 2rem; /* Scales with the root font size */
}Use Cases for EM:
EM units are useful when you want elements to scale based on the font size of their parent or themselves, making them ideal for nested components or when relative scaling within specific contexts is desired.
Component-Level Sizing:
- If you have a reusable component and want its child elements to scale relative to the parent’s size, EM works well. This is often the case in UI elements like buttons, cards, or navigation menus where the sizing of child elements needs to adapt based on the parent component’s font size.
Example:
.button {
font-size: 1.5em; /* Scales relative to parent font size */
padding: 0.5em 1em;
}Nested Layouts and Local Control:
- In cases where you want nested elements to scale based on their immediate parent’s font size (not the root element), EM offers greater flexibility.
- For example, in a navigation bar or card component, you might want buttons, labels, or icons to scale with the parent rather than the entire page.
Example:
.menu {
font-size: 1.2em; /* Sets the base font size for the menu */
}
.menu-item {
font-size: 1em; /* Inherits and scales based on .menu */
}Fine-Tuning Localized Sizing:
- EM allows for more granular control of the sizing within smaller or nested elements. For example, if you have a container with a specific font size, EM helps to ensure that padding, margins, or font sizes inside the container stay in proportion to it.
Example:
.box {
font-size: 1.2em;
padding: 1em; /* Padding will be proportional to the container's font size */
}Typography in Nested Elements:
- When working with nested typography, EM allows child elements to scale based on their direct parent. For instance, if you have a heading within a section of the page that should have a larger font size relative to the rest of the content, you can apply EM units.
Example:
.section {
font-size: 1.5em;
}
.section h2 {
font-size: 1.2em; /* Scales based on the section's font size */
}FAQ on EM vs REM
Why convert EM to REM?
Converting EM to REM offers baseline consistency. While EM units depend on parent elements, REM units tie directly to the root element. This dependency makes REM units more predictable in complex designs. Use a converter for precise conversion to streamline your workflow.
How do I calculate EM to REM manually?
To convert EM to REM manually, know the root font size. Typically it’s 16px. If an element is 2em, and the root is 16px, it’s 32px (2em * 16px). Convert it to REM by dividing by 16px (32px / 16px = 2rem). Simple math, but converters automate this.
Are EM or REM better for responsive design?
REM units offer more stability in responsive design. They’re easier to manage across different screen sizes because they reference the root element. EM can be nested and accumulate, complicating calculations. REMs streamline the process, allowing for more predictable scalability.
What’s the difference between EM and REM?
EM units rely on their immediate parent’s font size, while REM units reference the root element. This fundamental difference affects scalability and predictability. REMs ensure uniformity across the board, avoiding the cascading effect EM units might introduce in nested elements.
Can I switch from EM to REM in existing projects?
Sure, switch from EM to REM by identifying your base root size. Use an EM to REM converter tool to transform your current sizes. Update your CSS stylesheet accordingly, ensuring all sizes are consistent. This shift can simplify managing responsive and scalable designs.
Does the EM to REM converter tool work with all browsers?
Yes, most modern EM to REM converter tools are compatible with all major browsers. The underlying CSS units, EM and REM, are well-supported across browsers like Chrome, Firefox, Safari, and Edge. Always ensure your stylesheets meet browser compatibility standards.
How does an EM to REM converter improve my workflow?
Using a converter tool streamlines your CSS unit management. No need to manually calculate every size, saving valuable time. Enter EM values, and the tool gives REM equivalents. This ensures consistency, improves efficiency, and allows you to focus on design rather than calculations.
What role does an EM to REM conversion chart play?
Conversion charts serve as quick references for designers. Have a table of common EM values with their REM equivalents handy. This visual guide speeds up the design process, reducing computational errors. Use charts alongside converter tools for maximum efficiency in your workflow.
