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

The number you see on a monitor's label — 24 inches, 27 inches, 32 inches — refers to the diagonal measurement from the bottom-left corner to the top-right corner of the display area. This is the industry standard, and it's the only measurement that matters when you're comparing monitor sizes. The actual width and height vary depending on the aspect ratio (the shape of the screen), so two 27-inch monitors can have different widths and heights but the same diagonal.

If you want to know the exact size of a monitor you already own, you can measure it yourself with a tape measure or ruler. Measure from one corner of the screen to the opposite corner, staying on the glass or display surface itself — do not include the bezel (the plastic frame around the edge). Round to the nearest whole number. If you get 23.8 inches, it's a 24-inch monitor. If you get 26.9 inches, it's a 27-inch monitor.

Key Takeaways

  • Monitor size is always the diagonal measurement in inches, from corner to corner across the screen itself, not including the frame.
  • You can find your monitor's size on the original box, in the product manual, on the manufacturer's website, or by measuring it yourself with a tape measure.
  • Two monitors with the same diagonal size can have different widths and heights if they have different aspect ratios (16:9 versus 21:9, for example).
  • Common monitor sizes are 24, 27, 32, and 34 inches, though sizes range from 21 inches to 49 inches and larger.

How to find your monitor size if you don't know it

The easiest way is to check the original box or paperwork that came with the monitor. The size is always printed on the box and in the manual. If you no longer have those, look at the back or bottom of the monitor itself — many manufacturers print the model number there, and you can search that model number on the manufacturer's website to find the specifications.

On Windows, you can also check the display settings. Right-click on the desktop, select Display settings, scroll down, and look for a section labeled Display information or Advanced display settings. Windows does not always list the monitor size here, but it will show the resolution (like 1920 × 1080), and you can use that resolution along with your monitor's model number to narrow down the size.

On Mac, go to the Apple menu, select About This Mac, then click Displays. The monitor size may appear here, though newer Macs sometimes show only the resolution. If the size is not listed, search your monitor's model number on the manufacturer's website.

Why monitor size matters for your setup

Monitor size affects how much screen space you have for work or gaming. A 24-inch monitor is standard for most desks and fits comfortably at arm's length. A 27-inch monitor gives you noticeably more room without requiring you to move your head as much. Larger monitors (32 inches and up) are useful if you sit farther away or want to see multiple windows side by side, but they can feel cramped if your desk is small or you sit close to the screen.

Size also affects the physical footprint of the monitor on your desk. A 24-inch monitor with a 16:9 aspect ratio is roughly 21 inches wide and 12 inches tall. A 27-inch monitor is roughly 24 inches wide and 14 inches tall. A 34-inch ultrawide (21:9 aspect ratio) is roughly 32 inches wide and 14 inches tall. Measure your desk space before buying a larger monitor to make sure it fits.

How aspect ratio changes the width and height

Two monitors can have the same diagonal size but different widths and heights. This happens because of the aspect ratio — the relationship between width and height. A standard monitor has a 16:9 aspect ratio (wider than it is tall). An ultrawide monitor has a 21:9 aspect ratio (much wider). A square monitor has a 16:10 or 4:3 aspect ratio.

A 27-inch monitor with 16:9 aspect ratio is about 24 inches wide and 13.5 inches tall. A 27-inch monitor with 16:10 aspect ratio is about 23.5 inches wide and 14.7 inches tall — slightly narrower but taller. If you need to fit a monitor into a specific space, knowing both the diagonal size and the aspect ratio matters. You can find the aspect ratio on the product page or by dividing the resolution width by the resolution height (for example, 2560 ÷ 1440 = 1.78, which is 16:9).

Common monitor sizes and what they're used for

A 24-inch monitor is the most common size for office work, gaming, and general use. It fits on most desks, costs less than larger sizes, and sits at a comfortable viewing distance. Resolution is typically 1920 × 1080 or 2560 × 1440.

A 27-inch monitor is popular for gaming, video editing, and programming because it offers more screen space without being too large. Resolution is usually 2560 × 1440 or 3840 × 2160 (4K). It requires a bit more desk space than a 24-inch.

A 32-inch monitor is used for detailed work like photo editing, 3D modeling, and watching video. It sits farther from your eyes than a 27-inch, so the text and icons don't feel oversized. Resolution is typically 3840 × 2160 (4K) or higher. It takes up significant desk space.

An ultrawide monitor (typically 34 inches or larger with a 21:9 aspect ratio) is useful for multitasking, trading, and creative work where you want multiple windows visible at once. It's wider than a standard 27-inch but not much taller. These are less common and more expensive than standard sizes.

Measuring your monitor yourself

If you want to verify your monitor's size or you have an older monitor without clear labeling, you can measure it. Use a tape measure or a ruler. Place the zero end at one corner of the screen (the glass surface, not the plastic frame) and extend it diagonally to the opposite corner. Write down the measurement. If you get a number like 23.8 or 26.9, round to the nearest whole number — that's your monitor size.

Make sure you're measuring only the display area. Do not include the bezel or the stand. If your monitor is mounted on an arm or wall, the measurement is the same — measure the screen itself, not the mounting hardware.

Frequently Asked Questions

Is the monitor size the same as the screen resolution?

No. Size is the physical diagonal measurement in inches. Resolution is the number of pixels displayed (like 1920 × 1080). A 24-inch monitor and a 27-inch monitor can both have 1920 × 1080 resolution, but the 27-inch will show larger text and icons because the same number of pixels is spread across a larger area.

Does the bezel count toward the monitor size?

No. The bezel is the plastic or metal frame around the screen. Monitor size is measured only on the display area itself, from corner to corner of the glass. The bezel is not included in the measurement.

Can I use my monitor's model number to find its size?

Yes. The model number is usually printed on the back of the monitor or on the original box. Search the model number on the manufacturer's website (Dell, LG, ASUS, Samsung, etc.), and the specifications page will list the screen size, resolution, and dimensions.

What's the difference between a 27-inch monitor and a 27-inch TV?

Both are measured the same way — diagonally in inches. The difference is in how they're designed. Monitors are meant to be viewed up close at a desk, so they have higher pixel density and faster response times. TVs are meant to be viewed from across a room, so they have lower pixel density and are optimized for video playback rather than text clarity.

If I buy a new monitor, how do I know what size will fit my desk?

Measure your available desk space in width and height. Then look up the physical dimensions (width, height, and depth) of the monitor you're considering on the product page. The dimensions are usually listed in inches or centimeters. Compare them to your desk space to make sure there's room for the monitor and the stand, plus space for a keyboard and mouse.