Size is often the first and most important decision to make about your monitor. These are the most common sizes you'll come across, always measured diagonally across the screen. The following range from most common to least, and include different aspect ratios and resolutions that are often used at that size.
27-inch: This size has become the standard, offering enough screen size without overtaking your desk or stretching out the pixels too much at 1080p. If you're unsure of what to get, start here.
32-inch: The next most popular size, giving you that bit of extra screen real estate for multitasking. You'll just want to make sure your monitor has at least a 1440p resolution to keep the pixel density high enough. If 32 inches isn't big enough, there are even 40-inch or 43-inch monitors in the conventional 16:9 aspect ratio, though you'll really want to make sure you have a big enough desk for one of these.
34-inch: Curved, ultrawide monitors with a 21:9 aspect ratio and 34-inch screen size used to be odd, but these days, they've become an alternative to using two 27-inch screens.
24-inch: This smaller size has become less popular over the years, and I only recommend it if you're trying to squeeze a monitor onto a smaller desk or are a professional esports gamer.
There are other outliers, such as the absurd 49-inch, 32:9 behemoths, known as “super ultrawide” monitors, or 16-inch portable monitors that are meant to pair with your laptop.