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

When someone says a 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 monitor vary depending on the shape of the screen — a widescreen monitor takes up more horizontal space than a square one, even if both are the same diagonal size.

The bezel (the plastic frame around the screen) adds extra width and depth to the overall monitor, so the screen itself is slightly smaller than the monitor's total footprint. If you're measuring to see whether a monitor fits on your desk, you need to account for this frame, not just the screen diagonal.

Key Takeaways

  • Monitor size is always the diagonal measurement in inches, measured from corner to corner across the screen itself, not including the bezel.
  • You can find your monitor's size on the original box, in your computer's display settings, or by measuring the screen diagonal with a tape measure.
  • The bezel adds 1 to 3 inches to the monitor's total width and depth, so measure the whole unit if you need to know whether it fits your desk space.
  • Common monitor sizes are 21.5, 24, 27, 32, and 34 inches, with larger sizes taking up proportionally more desk space.
  • If you only know the screen resolution (like 1920×1080), you cannot determine the monitor size without additional information.

Check your monitor size in Windows display settings

Windows does not directly display your monitor's diagonal size in the settings menu, but you can find it through the manufacturer's information. Right-click on your desktop and select Display settings. Scroll down and click Advanced display settings. Look for the name of your monitor — it usually appears as a brand name followed by a model number, like "Dell S2721DGF" or "LG 27UP550".

Once you have the model number, search for it online along with the word "specs" or "specifications". The manufacturer's product page will list the diagonal screen size. If the model number is not visible in Advanced display settings, look at the physical monitor itself — most manufacturers print the model number on a sticker on the back or bottom of the unit.

Check your monitor size on a Mac

On macOS, click the Apple menu and select System Settings (or System Preferences on older versions). Go to Displays. The size information may appear in the resolution dropdown, but more often you'll need to identify the monitor model first. Look for the model number printed on the back or bottom of the monitor, then search for that model number online to find the diagonal size.

If you have multiple monitors connected, each one will appear as a separate entry in the Displays settings. Click on each one to see which model you're looking at.

Measure the screen diagonal yourself

If you cannot find the model number or the information online, you can measure the screen diagonal directly. Use a tape measure or a ruler and measure from the bottom-left corner of the screen to the top-right corner, or from the top-left to the bottom-right. Measure only the screen itself, not the bezel. Round to the nearest half-inch — a monitor that measures 23.8 inches is typically sold as a 24-inch monitor.

This method works for any monitor, including older models or displays without clear labeling. The measurement should match one of the standard sizes: 21.5, 24, 27, 32, or 34 inches are the most common, though other sizes exist.

Understand the difference between screen size and desk footprint

The diagonal measurement tells you the screen size, but not how much space the monitor takes up on your desk. A 27-inch widescreen monitor is wider than a 27-inch square monitor. The bezel also adds space — typically 1 to 3 inches on each side, depending on the model.

If you need to know whether a monitor will fit your desk, measure the total width and depth of the entire monitor unit, including the stand and bezel. Compare that to your available desk space. The monitor's height also matters if you're stacking monitors or placing one above another.

Common monitor sizes and what they mean

Most desktop monitors fall into a few standard sizes. A 24-inch monitor is the most common for office work and general use — it's large enough to see detail but small enough to fit most desks. A 27-inch monitor gives you more screen space for spreadsheets, video editing, or gaming without taking up drastically more room. A 32-inch monitor is considered large and is often used for professional work like photo editing or video production, or for gaming setups where you sit farther from the screen.

Ultrawide monitors, like 34-inch models, have a wider aspect ratio than standard widescreen displays. They take up more horizontal space but may not be taller than a 27-inch standard monitor. Smaller monitors, like 21.5 inches, are less common now but still appear in budget setups or as secondary displays.

Why resolution doesn't tell you the monitor size

Two monitors can have the same resolution — say, 1920×1080 — but different diagonal sizes. A 24-inch monitor and a 27-inch monitor can both display 1920×1080. The difference is that the 27-inch monitor spreads those pixels across a larger area, so each pixel is slightly bigger and text appears larger. This is why resolution alone cannot tell you the monitor size.

If you know both the resolution and the diagonal size, you can calculate the pixel density (pixels per inch), which affects how sharp the image looks. But to find the size, you need to look at the monitor itself or its documentation.

Frequently Asked Questions

Can I find my monitor size from the resolution alone?

No. Many different monitor sizes can display the same resolution. You need to check the monitor's model number, the original box, or measure the diagonal yourself. Resolution tells you how many pixels fit on the screen, not how large the screen is.

Does the bezel size affect the diagonal measurement?

No. The diagonal measurement is always the screen itself, from corner to corner of the actual display area. The bezel is the plastic frame around the screen and is not included in the size rating. However, the bezel does add to the monitor's total width and depth on your desk.

What if my monitor model number doesn't show up in a search?

Try searching for the brand name and any numbers or letters printed on the monitor. If it's a very old monitor, the manufacturer may no longer list it online. In that case, measuring the diagonal with a tape measure is your most reliable option.

Is a 27-inch monitor significantly larger than a 24-inch?

A 27-inch monitor has about 30 percent more screen area than a 24-inch, but the difference in width is smaller — usually 3 to 4 inches. The extra space is noticeable for work like spreadsheets or video editing, but the monitor doesn't take up drastically more desk room.

Why do manufacturers measure diagonally instead of width or height?

The diagonal measurement is a single number that works for any screen shape — square, widescreen, or ultrawide. Width and height vary depending on the aspect ratio, so a diagonal measurement is the only consistent way to compare monitors across different styles.