Monitor size is measured diagonally across the screen in inches, from one corner to the opposite corner

When someone says their monitor is 24 inches, they mean the distance from the bottom-left corner to the top-right corner measures 24 inches. This diagonal measurement is the standard way manufacturers label monitors, and it's the number you'll see on the box and in product listings. The actual width and height of the screen depend on the shape — a widescreen monitor and a square monitor of the same diagonal size will have different dimensions.

You can find your monitor's size by looking at the original box, checking the manual, or searching for the model number online. If you need to measure it yourself, use a measuring tape and run it from corner to corner across the screen itself, not including the plastic frame around it. Round to the nearest whole number — a monitor that measures 23.8 inches is typically sold as a 24-inch monitor.

Key Takeaways

  • Monitor size is always the diagonal measurement in inches, from one corner of the screen to the opposite corner.
  • The easiest way to find your monitor's size is to look at the original box, the manual, or search the model number online.
  • If you measure yourself, measure only the screen area, not the plastic bezel or stand, and round to the nearest whole number.
  • Two monitors with the same diagonal size can have different widths and heights depending on whether they are widescreen or square.
  • Common monitor sizes are 21.5, 24, 27, 32, and 34 inches, though sizes vary by manufacturer and purpose.

Finding the size from your monitor's label or documentation

The quickest way to learn your monitor's size is to look at the sticker on the back or bottom of the monitor itself. Most manufacturers print the model number and screen size on a label. The size appears as a number followed by inches — for example, "27 inches" or "27"" (the quotation mark is shorthand for inches).

If the label is worn or missing, check the original box or manual. The box usually has the size printed on multiple sides. If you no longer have the box, find the model number on the monitor (usually on the back or bottom) and search for it online — the manufacturer's website or a retailer's product page will list the screen size in the specifications.

How to measure your monitor if you can't find the size listed

Place a measuring tape at the bottom-left corner of the screen and stretch it diagonally to the top-right corner. Measure only the black or colored screen area itself — do not include the plastic frame (called the bezel) around the edges. Write down the measurement in inches.

If your tape measure shows 23.6 inches, round up to 24 inches. If it shows 26.9 inches, round down to 27 inches. Manufacturers use these rounded numbers in their product names, so your measurement may be slightly different from the official size. This small difference does not affect how the monitor works or how it looks on your desk.

Understanding the difference between diagonal size and actual width or height

Two monitors labeled 27 inches can have different widths and heights. A widescreen monitor (the most common type) is wider than it is tall. A square or nearly square monitor is closer to the same width and height. Both can measure 27 inches diagonally, but one will take up more horizontal space on your desk.

If you need to know the exact width or height — for example, to fit a monitor into a specific desk space — look up the full dimensions in the product specifications. These are usually listed as width × height × depth in inches or centimeters. The diagonal size alone does not tell you whether the monitor will fit your desk setup.

Common monitor sizes and what they mean for your workspace

Monitors typically come in sizes from 21.5 inches up to 34 inches or larger. A 24-inch monitor is the most common size for general office work and fits comfortably on most desks. A 27-inch monitor gives you more screen space without taking up dramatically more room. A 32-inch monitor is large enough that you may need to sit farther back or move your eyes more to see all of it at once.

Ultrawide monitors — those labeled 34 inches or larger — are wider than they are tall and are popular for video editing, programming, and gaming because they show more content side by side. The size number still refers to the diagonal measurement, so a 34-inch ultrawide is not as tall as a standard 34-inch monitor would be. When shopping, check both the diagonal size and the actual width to understand how much desk space you need.

Why manufacturers use diagonal measurement instead of width

The diagonal measurement became the standard because it gives a single number that applies to any screen shape. A 27-inch widescreen monitor and a 27-inch square monitor have the same diagonal but different widths and heights. Using the diagonal allows manufacturers to label monitors consistently without specifying the shape every time.

This system can be confusing when you are comparing monitors, because a 27-inch widescreen and a 27-inch square monitor look quite different on your desk. Always check the width and height in the full specifications if you are trying to fit a monitor into a specific space or comparing how much screen area you actually get.

Frequently Asked Questions

How do I measure my monitor if the measuring tape doesn't reach corner to corner?

Use a straightedge like a ruler or the edge of a piece of paper to mark where the diagonal line would be, then measure the marked line in sections. Alternatively, measure the width and height separately, then use an online calculator to find the diagonal — search "diagonal calculator" and enter the width and height.

Does the monitor size include the stand or just the screen?

The size refers only to the screen itself, not the stand or base. Measure from corner to corner of the actual display area. The stand can vary in size even between two monitors of the same screen size, so it does not affect the official measurement.

My monitor says 24 inches but measures 23.8 inches — is something wrong?

No. Manufacturers round to the nearest whole number for the product name. A monitor that measures 23.8 or 23.9 inches is sold as a 24-inch monitor. This small difference is normal and does not mean the monitor is defective or smaller than advertised.

Can I use the monitor size to figure out how much desk space I need?

The diagonal size alone is not enough. You also need the width and depth of the monitor with its stand. Look up the full dimensions in the product specifications, which list width, height, and depth. This tells you exactly how much space the monitor will take up on your desk.

What if my monitor is curved or has an unusual shape?

Even curved or ultrawide monitors are measured diagonally from corner to corner of the screen. The curve or unusual shape does not change how the size is measured or labeled. The diagonal measurement still applies the same way.