Rem vs Px: What’s the Difference for Your Website?

Pixels and rem are commonly used terms in web development, and understanding them is key to building high-quality websites. In this article, we’ll explain what they are and why it’s important to grasp the difference between the two.

Pixel: Definition

Pixels are a widely used unit of measurement in web development, as they allow you to define an element’s size on a screen with absolute precision. This makes pixels a popular choice for developers who want full control over element sizes on their website.

Using pixels

When you use pixels to define element sizes on your website, you can be certain that the element will have exactly the same size across all screens. However, this can also cause issues if you want your website to be responsive and display correctly on screens of different sizes. Pixels are fixed and do not automatically adapt to varying screen dimensions.

Advantages of pixels:

- Absolute precision in element sizing

- Full control over element dimensions

Despite these advantages, pixels can create problems if you want your website to display correctly on screens of different sizes. It’s therefore important to weigh the pros and cons before deciding to use pixels for your website design.

Rem: Definition

Rem is a relative unit of measurement that is based on the root font size to define an element’s size on a website. Rem units are more flexible than pixels and automatically adapt to different screen sizes.

Using rem

When you use rem to define element sizes on your website, you can be sure that the element will have a consistent size across all screens. This means your website can display correctly on screens of varying sizes, which is crucial for user experience.

Advantages of rem:

- Flexibility to adapt to different screen sizes

- Ensures an optimal user experience across all screen types

Using rem units gives you better control over how your website displays across different screen sizes, which is crucial for ensuring a responsive design and an optimal user experience. However, it’s worth noting that rem units can be more challenging for beginner developers, as they require an understanding of the parent font size and how they are used to define element sizes on the website.

Rem or pixel?

Pixels and rem units are two different measurement units used to define the size of elements on a website. Pixels provide absolute precision for element sizing but can cause issues if you want your site to display correctly across different screen sizes. Rem units, on the other hand, are more flexible and automatically adapt to various screen sizes, ensuring an optimal user experience.

It’s important to understand the pros and cons of each unit to determine which is best for your specific website. If you need full control over the size of certain precise elements, pixels may be the right choice. But if you want your site to display correctly across different screen sizes, rem units are the better option.

CSS clamp() and fluid typography in 2026

Beyond the rem vs. px choice, CSS clamp() introduces a third approach: fluid values. The clamp(min, preferred, max) syntax defines a size that adapts to the screen width without requiring media queries.

Practical example: font-size: clamp(1rem, 2.5vw, 1.5rem) sets a font size of 16px on mobile, which scales proportionally up to 24px on desktop. No need to write two separate media queries for text sizing.

Container queries (CSS @container) go further: they allow you to adapt a component’s style based on its parent container’s size, not the viewport. On Webflow, native CSS variables (since 2024) let you centralise these values and modify them in one place.

How many rem are in 1 pixel?

In reality, the answer depends on the browser and the parent font size defined on a website. By default, the parent font size is set to 16 pixels, meaning an element defined as 1rem will be 16 pixels. However, the parent font size can be set to a different value, which will affect how many rem correspond to 1 pixel.

Example of rem to pixel conversion

For example, if the parent font size is set to 10 pixels, an element defined as 1rem will be 10 pixels. If the parent font size is set to 20 pixels, an element defined as 1rem will be 20 pixels.

In other words, the number of rem in 1 pixel depends on the parent font size defined on a website or web browser. There is no standard answer, as it depends on how the site or browser is configured.

On Webflow, the tool handles the conversion itself!

When developing your site on Webflow, you can directly convert pixels to rem. To do this, simply add "/16" after the pixel value in the designer where you usually enter it, and Webflow will convert it to rem. Alternatively, you can download an extension like Finsweet to convert the entire page at once.

With Scroll agency, choose a 100% responsive website

At Scroll, we are Webflow experts and that’s why we’ve developed the Webflow agency to support you in creating your website. Our solutions are tailor-made and 100% responsive to adapt to all devices. No need to worry about pixel-to-rem conversion—our experts handle everything for you. If you have a new website or redesign project, don’t hesitate to contact us!