The three ways to measure your monitor

Monitor size is the diagonal distance from one corner of the screen to the opposite corner, measured in inches. A 24-inch monitor means the screen measures 24 inches corner-to-corner. You can find this number three ways: check the monitor itself for a label, look up the model number online, or measure the screen with a ruler or tape measure.

The physical size of the monitor (the bezel and stand) is larger than the screen itself, so measure only the visible display area, not the plastic frame around it. If you are buying a replacement monitor or troubleshooting a display problem, knowing the exact size helps you find compatible cables, stands, and mounting hardware.

Key Takeaways

  • Monitor size is measured diagonally across the screen in inches, and the label is usually on the back of the monitor or on the original box.
  • If you cannot find a label, search for your monitor model number (often printed on the back or bottom) on the manufacturer's website to find the specs.
  • You can measure the screen yourself with a ruler or tape measure from the bottom-left corner to the top-right corner, staying within the visible display area only.
  • Windows and Mac both show monitor resolution in display settings, but not the physical size — you must find the size through the label or model lookup.

Check the back or bottom of the monitor for a label

Most monitors have a sticker or printed label on the back panel or the bottom edge that lists the model number and screen size. Look for a label that says something like "24 inch" or "27 inch" or a model number like "Dell S2422HZ" or "LG 27UP550". The label may also include the resolution (like 1920x1080) and other technical details, but the screen size is usually listed clearly.

If the label is faded or missing, the original box or documentation that came with the monitor often has the size printed on it. Check any paperwork, manuals, or the box itself if you still have it. The size may also be printed on a sticker on the bottom of the monitor's base or stand.

Look up the model number on the manufacturer's website

If you cannot find a label on the monitor itself, write down the model number and search for it on the manufacturer's website. The model number is usually a combination of letters and numbers, often found on the back panel, the bottom of the stand, or sometimes on the front bezel near the power button. Common manufacturers include Dell, HP, LG, ASUS, BenQ, and Acer.

Go to the manufacturer's support or product page, enter the model number in the search box, and open the product specifications. The screen size will be listed in the specs section, usually near the top. You may also find the resolution, refresh rate, and other details that can help you understand your monitor's capabilities.

If you cannot find the model number, take a photo of any labels on the monitor and do a reverse image search, or describe the monitor's appearance and model details in a search engine — many tech forums and retailer sites catalog monitor specs by appearance and partial model numbers.

Measure the screen yourself with a ruler or tape measure

If you have a ruler, measuring tape, or even a piece of string and a ruler, you can measure the screen size directly. Place one end of the ruler at the bottom-left corner of the visible screen (not the plastic bezel) and measure diagonally to the top-right corner. Write down the measurement in inches. If you use a string, mark where it reaches the top-right corner, then measure the string against a ruler.

This method works best if the monitor is already mounted or sitting in front of you. Be careful not to press hard on the screen or damage any cables. If the measurement comes out to something like 23.8 inches or 27.2 inches, round to the nearest whole number — monitors are typically sold as 24-inch, 27-inch, 32-inch, and so on, even if the exact diagonal is slightly different.

Why monitor size matters for your setup

Knowing your monitor size helps you choose the right replacement if yours breaks, find compatible mounting arms or stands, and understand what resolution and refresh rate your monitor can support. Larger monitors (32 inches and up) often need a stronger stand or wall mount. Smaller monitors (under 20 inches) are less common now but may need special cables or adapters if you are replacing an older setup.

Monitor size also affects how much screen space you have for work or gaming. A 24-inch monitor at 1920x1080 resolution shows less detail than a 27-inch monitor at the same resolution, because the pixels are spread over a larger area. If you are shopping for a new monitor, knowing your current size helps you decide whether to stay with the same size or go larger.

What to do if you cannot find the size anywhere

If the label is completely gone, the model number is not visible, and you cannot measure accurately, post a clear photo of your monitor (showing the back, any visible labels, and the overall shape) on a tech forum like Reddit's r/techsupport or a manufacturer-specific community. Include any details you can see — brand name, color, approximate age, resolution if you know it, and any other markings. Other users can often identify the monitor from a photo and tell you the size.

You can also contact the monitor manufacturer's customer support directly with a photo and description. They may be able to identify the model and provide the specs, even if the label is missing. Keep in mind that support response times vary by company, so this route may take a few days.

Frequently Asked Questions

Does Windows or Mac tell me my monitor size?

No. Both Windows and Mac show you the resolution (like 1920x1080) and refresh rate in display settings, but not the physical screen size in inches. You must find the size through the monitor's label, model number lookup, or by measuring it yourself. The operating system does not know the physical dimensions of your screen.

Is the monitor size the same as the screen resolution?

No. Size is the diagonal measurement in inches. Resolution is the number of pixels displayed, like 1920x1080 or 2560x1440. Two monitors can be the same size but have different resolutions, or the same resolution but different sizes. Both numbers matter for different reasons — size affects how much space you have, and resolution affects how sharp the image looks.

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

Curved monitors are still measured diagonally across the visible screen area, just like flat monitors. The curve does not change how the size is reported. Ultrawide monitors (like 34-inch or 49-inch models) are also measured diagonally, so a 34-inch ultrawide is wider but shorter than a standard 34-inch monitor.

Can I use my monitor size to figure out what cables I need?

Monitor size alone does not tell you what cables you need. You need to know the inputs on the back of your monitor — common ones are HDMI, DisplayPort, USB-C, and VGA. Check the back of your monitor or the manual to see which ports it has, then get cables that match. The monitor size does not determine the cable type.

Why do some monitors say 23.8 inches instead of 24 inches?

Manufacturers measure the exact diagonal and round differently. A monitor might measure 23.8 inches diagonally but be marketed as a 24-inch monitor because that is the standard size category. The difference is usually less than half an inch and does not affect how the monitor works or looks on your desk.