As a website developer, you’ll see that several elements have sizing alternatives, such as PX, EM, REM, %, VW, or VH. But what exactly do those options mean, and when should you choose one over the other? Choosing the right option is one of the most important decisions website developers have to make. Consider this article your guide to choosing the right unit of measurement for your website. 

decisions website developers make

Absolute Units

PX: Although pixels (px) are relative to the viewing device’s DPI and resolution, they are considered absolute units. On the other hand, the PX unit is fixed on the device and does not change based on any other element. PX can be difficult for responsive web pages, but it is useful for keeping some elements’ sizes consistent. Using PX is a smart solution if you have elements that should not be scaled.

Relative Units

EM: This element is relative to the parent element. The browser’s default font is 16px, and 1em is not a fixed value across the entire page.

REM: REM is a new CSS3 relative unit, although it only refers to the HTML root element. It can not only change the font size proportionally by changing the root element, but it can also prevent the font size compounding chain reaction layer-by- layer.

%: % is relative to the parent element. 

VW and VH: Window units and related units are denoted by the letters VM, VH, Vmin, and Vmax. It is neither the page’s parent nor its root node. It’s defined by the size of the viewport, unit 1, which is about 1%. A viewport is the region of your browser where content is actually displayed. In other words, the part of your browser that doesn’t have toolbars and buttons. 

VW: the proportion of a window’s width (1vw means 1 percent of window width). 

VH: stands for window height as a percentage of the total height of the window. 

Vmin: takes the lesser of the current VW and VH values. 

Vmax: takes the greater of the current VW and VH values.

Difference Between EM and REM

Simply said, they differ according to genetics. REM is based on the root element, as previously stated (HTML). Whether a parent element has alternative sizes set, any child element that utilizes REM will use the HTML root size as its calculation point. 

On the other hand, EM depends on the parent element’s font size. The EM computation will be based on the parent element, not the root element, if the parent element has is a different size than the root element. As a result, nested elements that use EM for sizing can occasionally end up being a size you didn’t expect. However, if you need to specify the size for a certain area of a page, it gives you greater fine-grained control.

What About the Others? 

PX, EM, and REM are largely used for font sizing. %, VW, and VH are mostly used for padding, margins, spacing, and widths/heights.

To recap, VH stands for “viewport height,” which is the height of the visible screen. 100VH would be the complete height of the screen or 100 percent of the viewport’s height. VW stands for “viewport width,” which is the width of the viewable screen. The width of the viewport, or the full width of the screen, would be represented by 100VW. Regardless of the viewport size, percent represents a percentage of the parent element’s size.

Decisions Website Developers Must Make 

At the end of the day, there is no perfect answer to the question of which unit a web developer should use. In general, it’s better to use one of the relative units rather than PX if you want your web page to render a great responsive design. If you need to ensure that an element does not resize at any breakpoint and remains the same regardless of whether the user has selected a different default size, use PX. Even if the outcomes aren’t ideal, PX units maintain consistency.

EM: Because EM is relative to the font size of the parent element, you can use it to scale the element’s size to that of its parent.

REM: is related to the root (HTML) font size, therefore use REM if you want the element’s size to be scaled depending on the root size, regardless of the parent size. If you’ve tried EM and are having problems with size because you have a lot of nested components, REM is probably the better option.

VW: is helpful for producing full-width elements (100%) that span the complete width of the viewport. Of course, any percentage of the viewport’s width can be used to achieve various purposes, such as 50% for half the width and so on.

VH: is great for building full-height items that fill the entire viewport’s height (100 percent). Of course, any percentage of the viewport’s height can be used to achieve various purposes, such as 50% for half the height, and so on.

%: % is similar to VW and VH, but it is not a length that is proportional to the width or height of the viewport. Instead, it’s a percentage of the width or height of the parent element. For example, percentage units are frequently used to set the width of margins.

When it comes to decisions website developers must make, this is an important one. If you are still unsure which unit you should go with, contact New Target. Our expert web developers have all the skills and knowledge to make all the right decisions for your website.

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