REM to PX Converter: The Ultimate CSS Unit Conversion Tool
Our REM to PX Converter is a straightforward tool designed to help you quickly translate REM units into their pixel equivalents for your web projects. By simply entering a base font size and the REM value, you can instantly get the exact pixel (PX) value, streamlining your CSS workflow for responsive and accessible design.
Instantly convert REM units to pixels (and back) based on your root font size. Change any value to see real-time results.
REM to PX
PX to REM
Conversion Table
| REM | Pixels |
|---|
Other Calculators
How to Use Our REM to PX Converter
Using this converter is a simple two-step process. The calculation depends on a “base” value which you can also adjust.
Base Font Size (in Pixels): This is the font size of the root element of a webpage (the
<html>tag). By default, virtually all web browsers set this to16px. Our calculator defaults to this value, but you can change it if your project uses a different base size.REM Value: Enter the REM value you wish to convert into pixels. This can be a whole number (like 2), a decimal (like 1.5), or a fraction (like 0.75).
The calculator will instantly provide the converted pixel value in the results field.
Understanding Your Results
The number you see in the results box is the pixel equivalent of the REM value you entered, based on the specified base font size. The conversion follows a very simple formula.
The REM to PX Formula
The relationship between REMs and Pixels is a direct multiplication:
Concrete Example:
Let’s say you want to convert 2.5rem to pixels, and your project uses the standard base font size of 16px.
2.5rem×16px=40px
So, 2.5rem is equivalent to 40px in this context. If you were to change the base font size to 20px, the same 2.5rem would then equal 50px. Our converter does this math for you instantly, saving you time and preventing errors.
Common REM to PX Conversion Chart (Base 16px)
For quick reference, here is a chart of common conversions using the default browser base font size of 16px.
Frequently Asked Questions
What exactly is a REM unit in CSS?
REM stands for “Root Em”. It is a relative CSS unit of measurement. Unlike an absolute unit like a pixel (PX), a REM’s value is relative to the font size of the root element of the HTML document. The root element is the <html> tag. By default, this is 16px in most browsers, so 1rem equals 16px, 2rem equals 32px, and so on.
Why should I use REMs instead of Pixels (PX)?
The primary reason to use REMs over pixels is accessibility.
When you size fonts, padding, margins, and other elements in pixels, you are defining a fixed size. If a user with a visual impairment goes into their browser settings and tries to increase the default font size to make text more readable, elements sized with px will not scale up. The text might get bigger, but the layout containing it will not, leading to broken designs and overlapping text.
When you use rem units, all your sizes are relative to the root font size. If a user changes their browser’s default font size from 16px to 24px, your entire layout scales up proportionally. A heading that was 2rem (32px) automatically becomes 48px, and a margin of 1rem (16px) becomes 24px. This creates a truly responsive and accessible experience for all users.
What is the difference between REM and EM units?
This is a frequent point of confusion. Both are relative units, but their context is different.
REM (Root Em): Is relative only to the root (
<html>) font size. This makes it predictable and consistent. No matter how deeply nested an element is,1remwill always equal the same value throughout your document.EM: Is relative to the font size of its direct parent element. This can be powerful, but also tricky. If you have a
<div>withfont-size: 20px, then for any child element inside that div,1emwill equal20px. If you nest another element inside that child and change its font size, theemvalue changes again. This cascading effect can make sizing unpredictable and hard to manage, which is whyremis now preferred for general layout spacing and font-sizing.
How do I set the base font size for my website?
You set the base font size by applying a font-size property to the <html> selector in your main CSS file.
CSS
html {
font-size: 16px; /* This is the default, but you can explicitly set it */
}
Setting this value allows you to control the base for all rem calculations on your site.
Is it a good practice to change the base font size from 16px?
This is a debated topic. One popular technique, known as the “62.5% trick,” involves setting the root font size to 62.5%. Since 16px * 62.5% = 10px, this makes the math for rem units very easy: 1rem = 10px, 1.6rem = 16px, 2.4rem = 24px, etc.
CSS
html {
font-size: 62.5%; /* Makes 1rem = 10px */
}
However, many accessibility advocates argue against this. They contend that overriding the user’s default browser setting with a percentage can interfere with their expected text size adjustments. The modern, recommended approach is to leave the browser default alone and work with 16px as your base. The math is slightly harder (e.g., 24px is 1.5rem), but tools like our REM to PX converter make this trivial.
How do I convert PX to REM?
To convert from pixels to REMs, you just reverse the formula:
Concrete Example:
You want to convert 24px to REMs, assuming a base font size of 16px.
24px÷16px=1.5rem
Should I use REMs for everything, including padding, margins, and borders?
It’s a common best practice to use rem units for most properties, especially font-size, padding, margin, width, and height. This ensures that your entire layout scales proportionally, maintaining visual harmony when the user adjusts their base font size.
However, there are exceptions. Some developers prefer to use px for elements that should never change size, such as a 1px border or a very specific box-shadow offset. The key is consistency and ensuring your design decisions support accessibility.
Can I use decimal values for REMs?
Absolutely. Using decimal values like 1.125rem or 0.875rem is standard practice and necessary to achieve specific pixel-perfect designs while still benefiting from the scalability of rem units. Browsers are perfectly capable of rendering fractional pixel values.
Why does my font look blurry when using REMs?
This is a myth that stems from old browser rendering engines. Modern browsers have sub-pixel rendering and handle fractional pixel values (which can result from rem conversions) without any issues. If you notice blurry fonts, it’s more likely due to font-smoothing properties, font file quality, or specific OS-level rendering settings, not the use of rem units themselves.
Does using REM units affect my website’s SEO?
Using rem units has a positive, albeit indirect, effect on SEO. Google’s ranking factors include user experience metrics like mobile-friendliness and accessibility. A website built with rem units provides a better, more accessible experience for users with visual impairments and scales more gracefully on different devices. By improving the user experience, you are sending positive signals to search engines that your site is high-quality and user-friendly, which can contribute to better rankings.
Now that you’ve mastered responsive sizing with our REM to PX Converter, you can style your elements perfectly. Create stunning visual effects for your components with our CSS Box Shadow Generator and build flexible, modern layouts with our interactive CSS Flexbox Generator.
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