REM to EM Converter

Convert REM to EM effortlessly with our REM to EM converter. Simplify your CSS font size adjustments for responsive design with accurate conversions.

REM to EM Manual Table Conversion

We’re assuming the standard default browser font-size of 16px

REMEM
0.01rem0.01em
0.03rem0.03em
0.05rem0.05em
0.08rem0.08em
0.1rem0.1em
0.15rem0.15em
0.2rem0.2em
0.5rem0.5em
1rem1em
2rem2em
3rem3em
4rem4em
5rem5em
6rem6em
8rem8em
10rem10em
15rem15em
20rem20em
30rem30em
40rem40em
50rem50em
60rem60em
80rem80em
100rem100em

EM to REM

EMREM
0.01em0.01rem
0.03em0.03rem
0.05em0.05rem
0.08em0.08rem
0.1em0.1rem
0.15em0.15rem
0.2em0.2rem
0.5em0.5rem
1em1rem
2em2rem
3em3rem
4em4rem
5em5rem
6em6rem
8em8rem
10em10rem
15em15rem
20em20rem
30em30rem
40em40rem
50em50rem
60em60rem
80em80rem
100em100rem

REM vs EM

AspectREMEM
DefinitionREM stands for “Root EM.” It’s relative to the root font size, typically the <html> element’s font size.EM is relative to the font size of the element to which it is applied.
RelationshipAlways relative to the root element’s font size (default is usually 16px).Relative to the parent element’s font size.
ConsistencyMore consistent across different elements since it only depends on the root element’s size.Can be less predictable as it compounds based on the parent element’s size, leading to potential scaling issues.
Use CasesIdeal for setting global, consistent font sizes, margins, padding, and responsive layouts.Best for local adjustments like small spacing or elements relative to their immediate context.
Scaling BehaviorScales uniformly with the root element’s font size, ensuring consistency across the design.Can scale unexpectedly when nested elements inherit different sizes from their parents.
Common ApplicationsPreferred for responsive typography and layouts that need to scale predictably across devices.Useful when designing elements that should be relative to their parent container rather than the root.
InheritanceDoes not compound when nested inside other elements, always relative to the root size.Compounds when used in nested elements, which can lead to unintended size inflation.
ReadabilityEasier to manage and calculate since it remains consistent throughout the document.Requires more careful management to avoid unintentional size growth, especially in deeply nested elements.
ResponsivenessWorks well for designing responsive layouts, making it easier to adjust the entire site by changing the root size.Can cause issues in responsiveness when multiple nested elements have varying em values.
Examplefont-size: 2rem; /* 32px if root is 16px */font-size: 2em; /* 2x the size of the parent element's font-size */

What is REM in CSS?

REM (Root Em) is a unit of measurement in CSS used for sizing elements on a webpage. It is relative to the font size of the root element (<html>), rather than the font size of the parent element (which is what EM is based on).

Here’s a more detailed breakdown of REM:

  1. Root Reference: REM is based on the font size of the root element (<html>). By default, browsers usually set this to 16px, so 1 REM is often equal to 16px unless modified.
  2. Consistency: Since REM is relative to the root font size, it ensures more consistent scaling across different elements on a webpage. This is especially useful in responsive design, where consistent spacing and typography scaling are important.
  3. Difference from EM: Unlike EM, which is relative to the font size of the parent element, REM is always relative to the root. This avoids the compounding effect that can occur with EM when nesting elements (since EM units multiply as they cascade down).
  4. Advantages:
    • Scalability: Changing the root font size scales all elements that use REM accordingly. This allows for easy adjustments for different screen sizes or user accessibility preferences.
    • Control: It provides better control over layout compared to EM, which can be more unpredictable due to its dependency on parent elements.

For example, if the root font size is 16px:

  • 1 REM = 16px
  • 2 REM = 32px
  • 0.5 REM = 8px

Using REM can make your website more responsive and user-friendly.

What is EM in CSS?

EM is another unit of measurement in CSS used to size elements relative to the font size of their parent element. Here’s a detailed breakdown of EM:

  1. Relative to Parent Font Size: EM is a relative unit that is based on the font size of the element’s parent. For example, if a parent element has a font size of 16px, 1em will be equal to 16px for that element. If the parent font size is 20px, then 1em will equal 20px.
  2. Scaling with Parent Size: Because EM is relative to the parent element’s font size, changes in the parent element’s size cascade down to its children, allowing nested elements to scale proportionally. However, this can also lead to unintended scaling if not carefully managed, especially when multiple nested elements use EM.
  3. Compounding Effect: One thing to watch for with EM is that when elements are nested, the EM value of a child element is multiplied by the EM value of its parent. For example, if a parent element is set to 1.5em (relative to its own parent), and a child element inside it is set to 2em, the child’s size will be 2 times the parent’s size (which is already scaled by 1.5em), leading to more complex scaling.
  4. Common Use: EM is commonly used for properties like font size, padding, and margin, where you want the element’s size to change relative to the font size of its parent element. This allows for a responsive and proportional design.
  5. Advantages:
    • Flexible Sizing: EM allows for more flexible and responsive designs because the size of elements can scale relative to the parent’s font size.
    • Nested Proportions: It provides a way to maintain proportional relationships between nested elements when the parent’s size changes.
  6. Difference from REM: While REM is based on the root element’s font size, EM is always relative to the closest parent element’s font size, which can lead to more variability when you have deeply nested elements.

Example:

If a parent element has a font size of 16px and you set a child element to 1.5em:

  • 1.5em would be 1.5 * 16px = 24px.

If you nest another element within that child and set it to 2em, it would be:

  • 2em relative to the child’s size of 24px = 2 * 24px = 48px.

This relative scaling can be useful but also requires careful management in deeply nested structures.

Use Cases of EM and REM

Both EM and REM have specific use cases in CSS design, and choosing between them depends on the layout requirements, scalability, and how you want the sizing of elements to behave. Here’s a breakdown of their use cases:

Use Cases of EM:

  1. Relative Scaling to Parent Element: EM is useful when you want an element’s size (like font size, padding, or margin) to scale relative to its parent element. This is especially helpful when creating components that adapt to the size of their containing elements.
    • Example: When creating reusable components or modular elements, EM can help ensure that the internal elements scale based on the parent component’s size, making it flexible for different contexts.
  2. Proportional Sizing for Nested Elements: EM allows nested elements to scale proportionally. This is useful when you want each child element’s size to increase or decrease based on its parent’s size, allowing for fluid, proportional design.
    • Example: In typography-heavy designs where headings, subheadings, and text elements should scale proportionally to each other based on the container they are in.
  3. Consistent Spacing with Font Size Changes: EM can be used for paddings, margins, and other spacing properties, allowing those spacings to adjust automatically when the font size of a parent element changes.
    • Example: If a section of a page increases in font size (like inside a feature box), the padding and margins can also increase using EM, keeping the layout proportional.
  4. Responsive Typography: When you want to adjust text sizes based on the surrounding elements or their containers, EM can help to ensure the text scales appropriately within those containers.
    • Example: In a sidebar or a card element where the text size should adjust based on the size of the container, EM ensures that it scales as the parent container grows or shrinks.

Use Cases of REM:

  1. Global Consistency: REM is ideal when you want a consistent size across the entire website, regardless of where the element is located in the document hierarchy. This makes REM great for maintaining uniformity in layouts and typography across the site.
    • Example: Setting font sizes globally using REM ensures that text elements will all scale relative to the root element (<html>), regardless of their parent elements, maintaining consistency throughout the design.
  2. Responsive Design: REM is widely used in responsive design because it allows you to easily adjust the size of all elements by changing the root font size (commonly done in media queries). This makes it easier to manage scalable layouts for different screen sizes.
    • Example: By adjusting the root font size in a media query, you can scale the entire layout up or down for different devices (mobile, tablet, desktop), making it simpler to manage responsive designs.
  3. Accessibility: REM is helpful when designing for accessibility because users who have customized their browser settings to increase or decrease the base font size will see appropriate scaling for all elements using REM. This ensures a better user experience for those with visual impairments.
    • Example: If a user increases their browser’s default font size, elements sized in REM will scale up accordingly, maintaining readability and layout integrity without breaking the design.
  4. Avoiding Nested Element Issues: REM is preferred when you want to avoid the cascading, compounding effects of EM in deeply nested elements. Since REM is relative to the root font size, the size doesn’t compound through nested elements.
    • Example: When creating complex layouts with multiple nested elements (like navigation bars, forms, or grids), using REM ensures that elements do not inadvertently become too large or too small as a result of nested parent elements.
  5. Typography for Consistent Text Sizing: Using REM for typography ensures that all text sizes are scaled relative to the root font size, which makes it easier to manage typography site-wide, without worrying about inheritance from parent elements.
    • Example: Setting body text at 1rem (16px by default) and headers at 2rem ensures that all text sizes will adjust proportionally if you change the root font size, giving you control over scaling without inconsistencies.

Summary of Use Cases:

  • Use EM:
    • When you want to size elements relative to their parent.
    • For reusable components where internal elements need to scale with the parent.
    • In typography-heavy layouts where nested elements should scale proportionally.
    • For consistent spacing that adapts to font size changes.
  • Use REM:
    • When you need global consistency in font sizes and layout.
    • For responsive design, allowing easy scaling with media queries.
    • For accessibility, ensuring elements respond to user-set font sizes.
    • To avoid compounding effects in deeply nested structures.
    • For consistent typography that adjusts based on the root font size.

FAQ on REM vs EM

What is a REM to EM converter?

REM to EM converter is a handy tool in web development that helps you translate font sizes or other measurements from REM units to EM units. It’s essential for managing responsive design, ensuring that typography scales fluidly across various devices, keeping consistent and readable layouts.

Why would I need to convert REM to EM?

Converting REM to EM is crucial when tweaking your CSS for responsive design. Since REM is relative to the root element and EM to its parent’s font size, this conversion helps manage nested elements better and ensures a harmonious design across your web typography and CSS layout.

How does a REM to EM converter work?

The converter takes a value in REM and recalculates it into EM based on the relationship between the root font size and the parent font size. This allows you to maintain proportionality in web design, adhering to the principles of CSS and improving design consistency.

Are there any best practices when using REM and EM units?

Yes, always establish a base font size, typically in your html or body tag. Use REM for elements where global scaling is desired and EMs for local adjustments. This method ensures better accessibility design and fluid typography, keeping your design metrics accurate.

Can I use a REM to EM converter for other CSS units?

Definitely. Many converters also include options for pixel to REM or pixel to EM, catering to diverse web development needs. These tools help translate various CSS units, providing flexibility in your design metrics and ensuring cross-browser compatibility.

Yes, frameworks like Bootstrap and Foundation support both REM and EM units for their responsive design components. Utilizing these units in your CSS frameworks ensures that your design remains scalable and adaptable, providing a more consistent user experience across devices.

How does using REM and EM impact responsive web design?

Using REM and EM units allows for more fluid and scalable responsive web design. Since REM units are relative to the root font size and EM to the parent, this approach facilitates better responsive design and ensures design patterns adapt neatly to various screen sizes.

What tools can help me convert REM to EM?

There are many online unit conversion tools available, such as calculators embedded in web development platforms or standalone converters. These tools assist in maintaining design guidelines, ensuring that your CSS remains consistent and your typography scales appropriately.

How do REM and EM units affect accessibility?

Using REM and EM units can significantly improve accessibility by allowing users to adjust text size globally or locally without breaking the layout. This ensures that your web design adheres to accessibility compliance tools and provides a user-friendly experience for individuals with visual impairments.

Can I manually convert REM to EM without a tool?

Yes, you can manually convert REM to EM using some basic math. Simply determine the relationship between your root font size and the parent font size. Then, multiply your REM value accordingly to get the EM equivalent. This manual method can furnish insights into fluid design practices and precise typography.

 

 

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