The quickest way to find your monitor size

Your monitor size is the diagonal measurement in inches from one corner of the screen to the opposite corner—measured across the glass, not the frame. The easiest way to find it is to look at the sticker on the back or bottom of your monitor, check your monitor's manual, or search the model number online. If you have already thrown away the manual, the model number is usually printed on a label on the back of the monitor or sometimes on the bottom bezel.

If you cannot find a label, you can measure the screen yourself with a ruler or measuring tape. Measure from the bottom-left corner of the actual display glass to the top-right corner. Round to the nearest whole number—most monitors come in standard sizes like 21.5, 24, 27, 32, or 34 inches. This measurement will be close enough for any practical reason you need the size.

Key Takeaways

  • Monitor size is the diagonal measurement across the screen glass, measured from corner to corner.
  • The model number on the back of your monitor can be searched online to find the exact size in the manufacturer's specifications.
  • If you measure the screen yourself with a ruler, round to the nearest whole number since monitors are sold in standard inch increments.
  • Windows and Mac both display monitor information in display settings, though this method is less reliable than physical measurement or the label.

Finding the model number and looking it up online

The model number is your fastest path to the correct size. Look on the back of the monitor for a white or silver label—it usually contains the brand name, model number, and sometimes the screen size printed right there. The model number is often a combination of letters and numbers, like "LG 24UP550" or "Dell S2721DGF."

Once you have the model number, open a web browser and search for it along with the word "specifications" or "specs." The manufacturer's product page will list the screen size in the first few lines. If the manufacturer's site does not come up first, try adding the brand name to your search, like "Dell S2721DGF specifications."

If the label is worn or missing, check inside the battery compartment on the back of the monitor or look at the bottom bezel where the stand connects. Some monitors also print the model number on the power cable or the original box if you still have it.

Measuring your screen yourself

You will need a ruler, measuring tape, or even a piece of string and a ruler. Measure from the bottom-left corner of the screen glass to the top-right corner in a straight diagonal line. Do not measure the frame or the plastic bezel—only the glass display area itself. Write down the number in inches.

Monitor sizes are always sold in whole-inch increments: 21.5, 24, 27, 32, 34, and 38 inches are the most common. If your measurement comes out to 23.8 inches, that is a 24-inch monitor. If it is 26.9 inches, round to 27 inches. This rounding is normal because manufacturers measure to the nearest tenth of an inch, but they market in whole numbers.

This method works well if you need the size right now and do not want to search online. The measurement will be accurate enough for any reason you need it—ordering a replacement stand, checking desk space, or comparing to another monitor.

Checking your operating system settings

Windows and Mac both show monitor information in their display settings, though this method is less reliable than physical measurement. On Windows, right-click on your desktop and select "Display settings." Scroll down and look for "Display information"—some versions show the monitor model and resolution, but not always the screen size. On Mac, click the Apple menu, go to "System Preferences," then "Displays," and look for the resolution and model information in the "About Displays" button.

The operating system usually detects the monitor model from the EDID (Extended Display Identification Data) information sent by the monitor itself. This works well most of the time, but older monitors or monitors connected through certain adapters may not report their information correctly. If the settings show a model number, you can search that number online to confirm the size.

What to do if you cannot find the model number

If the label is completely missing and you cannot find the model number anywhere, measuring the screen is your most reliable option. Measure diagonally from corner to corner as described above, and round to the nearest whole number. This will give you the correct size in the standard increments monitors are sold in.

Another option is to look at the resolution and aspect ratio of your monitor, then cross-reference common monitor sizes. A 1920 × 1080 monitor is usually 21.5 or 24 inches. A 2560 × 1440 monitor is typically 27 inches. A 3440 × 1440 ultrawide is usually 34 inches. This is not foolproof—multiple sizes can share the same resolution—but it narrows down the possibilities. You can find your resolution in Windows display settings or Mac system preferences.

Common monitor sizes and what they look like

Most desktop monitors fall into a few standard sizes. A 24-inch monitor is the most common size for office work and general use—the screen is about 21 inches wide and 12 inches tall. A 27-inch monitor is popular for gaming and design work and is noticeably larger without taking up excessive desk space. A 32-inch monitor is quite large and works well if you sit far from your desk or want to see multiple windows side by side.

Ultrawide monitors, which are wider than they are tall, come in 29, 34, and 38-inch sizes. These are measured the same way—corner to corner diagonally—but they feel much wider than a standard monitor of the same size because of their aspect ratio. Laptop screens are measured the same way but are usually smaller, typically 13 to 17 inches.

Why knowing your monitor size matters

You might need to know your monitor size to order a replacement stand, choose a monitor arm, or check whether a new monitor will fit your desk space. Monitor size also affects how much screen real estate you have for work or gaming—a 27-inch monitor gives you significantly more space than a 24-inch, but it also takes up more room and may require you to move your head more to see the corners.

If you are shopping for a new monitor, knowing your current size helps you decide whether to stay the same or upgrade. It also helps you understand monitor specifications when you are comparing options online, since screen size is one of the first things listed in any product description.

Frequently Asked Questions

Is monitor size measured diagonally or across the width?

Monitor size is always the diagonal measurement from one corner to the opposite corner. A 24-inch monitor is not 24 inches wide—it is 24 inches measured diagonally across the glass. The actual width is usually around 21 inches, and the height is around 12 inches.

Can I find my monitor size in Windows or Mac settings?

Windows and Mac display settings may show your monitor model number, which you can search online to find the size. However, they do not always display the screen size directly. Measuring the screen yourself or checking the label on the back is more reliable.

What if my monitor size is between two standard sizes?

Monitors are manufactured in standard sizes, so your measurement should round to one of them. If you measure 23.8 inches, that is a 24-inch monitor. If you get 26.9 inches, round to 27 inches. Manufacturers measure to the tenth of an inch but market in whole numbers.

Does the monitor frame count toward the size measurement?

No. Measure only the glass display area, not the plastic bezel or frame around it. Measure from the corner of the actual screen to the opposite corner of the actual screen.

Where exactly is the model number on my monitor?

The model number is usually on a white or silver label on the back of the monitor, often near the power cable connection. Some monitors also print it on the bottom bezel, inside the battery compartment, or on the stand. Check all these places before assuming the label is missing.