REM to Pixel Converter | Fast & Accurate (Custom Base)
How to Convert REM to Pixels
Converting REM to PX is essential for modern web development, allowing you to translate scalable CSS units into absolute pixel values.
To use the converter above:
- Enter Base Size: The default industry standard is 16px (the default font-size of most browsers), but you can adjust this if your CSS defines a different root font size (e.g.,
html { font-size: 62.5%; }which equals 10px). - Enter REM Value: Type the rem amount you want to convert.
- Get Result: The tool instantly calculates the equivalent pixel value.
While converting REM to pixels is great for understanding your final output, modern responsive design often requires you to do the opposite. When you are taking dimensions from a design tool like Figma or Photoshop, you will likely need to convert pixels to REM to ensure your CSS remains scalable and accessible.
Video tutorial: How to use rem to pixels converter
What is a REM unit?
The REM (Root EM) unit is a relative CSS unit widely used in responsive web design. Unlike pixels (px), which are absolute and fixed, REM units are relative to the root element of your HTML document (usually the <html> tag).
-
Scalability: Because REM relies on the root size, changing one value in your CSS can scale typography and spacing across your entire website.
-
Accessibility: REM units respect the user’s browser settings. If a visually impaired user increases their browser’s default font size for better readability, layouts built with REMs will scale up accordingly. Layouts built with fixed Pixels will not.
The REM to PX Formula
If you need to calculate the conversion manually or write a function in JavaScript/Sass, here is the math behind the calculation:
Pixels = REM * BaseFontSize
Example Calculation: If your website uses the standard 16px base and you want to convert 2.5rem:
2.5 * 16 = 42px
REM vs. Pixel: Which should you use?
| Feature | Pixels (px) | REM |
|---|---|---|
| Type | Absolute Unit | Relative Unit |
| Scalability | Fixed size (does not scale) | Scales with root element |
| Best For | Borders, thin lines, shadows | Font sizes, padding, margins, media queries |
| Accessibility | Poor (ignores user preferences) | Excellent (respects user preferences) |
Pro Tip: Modern CSS best practices suggest using REM for font sizes and spacing (margins/padding) to ensure your site is accessible and responsive. Use Pixels only for elements that should never change size, such as 1px borders.
Common REM to Pixels Conversion Table (Base 16px)
This quick reference list assumes the standard browser default base size of 16px.
| Rem | Pixel |
|---|---|
| 0.125 rem | 2 px |
| 0.2 rem | 3.2 px |
| 0.25 rem | 4 px |
| 0.5 rem | 8 px |
| 1 rem | 16 px |
| 1.5 rem | 24 px |
| 1.8 rem | 28.8 px |
| 2 rem | 32 px |
| 2.5 rem | 40 px |
| 3 rem | 48 px |
| 3.5 rem | 56 px |
| 4 rem | 64 px |
| 4.5 rem | 72 px |
| 5 rem | 80 px |
| 5.5 rem | 88 px |
| 6 rem | 96 px |
| 6.5 rem | 104 px |
| 7 rem | 112 px |
| 7.5 rem | 120 px |
| 8 rem | 128 px |
| 8.5 rem | 136 px |
| 9 rem | 144 px |
| 9.5 rem | 152 px |
| 10 rem | 160 px |
| 10.5 rem | 168 px |
| 11 rem | 176 px |
| 11.5 rem | 184 px |
| 14 rem | 224 px |
| 15 rem | 240 px |
| 16 rem | 256 px |
| 24 rem | 384 px |
| 28 rem | 448 px |
| 64 rem | 1024 px |
Frequently Asked Questions (FAQ)
How many pixels is 1rem?
By default, in most modern browsers, 1rem equals 16 pixels. This is based on the root HTML font size. However, if a user changes their browser’s default font size for accessibility, the pixel value of 1rem will scale accordingly.
How do I convert pixels to rem?
To convert PX to REM, use the formula: Pixels / Root Font Size=REM. For example, if your base size is 16px and you want to convert 24px: 24 / 16=1.5rem.
Why should I use rem instead of px for web design?
Using rem is a best practice for web accessibility. Unlike fixed pixels, rem units allow the entire layout to scale if a visually impaired user increases their browser’s default text size, ensuring your site remains readable and compliant with [W3C Accessibility Guidelines](www.w3.org).
What is 1rem in Tailwind CSS?
In [Tailwind CSS](tailwindcss.com), the default spacing and font-scale are based on a 16px root. Therefore, text-base (1rem) is 16px, and p-4 (1rem) is 16px. If you change the base font size in your CSS, all Tailwind rem-based utilities will update automatically.
How to change the default rem size to 10px?
Many developers set the HTML font-size to 62.5% (html { font-size: 62.5%; }). Since the default is 16px, 62.5% makes 1rem=10px, which makes manual “PX to REM” math much easier (e.g., 14px becomes 1.4rem).
Why is my REM conversion not working?
Ensure you know the actual base size of your project. If you are using a framework like Tailwind or Bootstrap, check their default configuration. If the user has changed their browser’s default font size, 1rem will no longer equal 16px on their specific screen.
Is REM better than EM?
Both are relative units, but they behave differently. REM is relative to the root (html) element, making it consistent and predictable. EM is relative to the parent element, which can cause “compounding” issues where fonts get unintentionally huge or tiny if nested deeply. For most spacing and text needs, REM is safer.