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Screen Size Checker
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Estimated

Screen size checker

Your screen size in inches and cm, at once. It is an estimate from your screen's pixels. For the exact size, match a bank card to the screen.

Your screen size

Estimated

 

Drawing of your screen's shape
Resolutiondevice pixels
 
ScreenCSS pixels
 
Pixel ratiodevice pixels per CSS pixel
 
Aspect ratiowidth to height
 
Pixel densityrendered pixels per inch
 
Browser viewportthe part that shows the page
 
Viewport sizereal size
 
Available screenwithout taskbar or Dock
 
Browser windowCSS pixels
 
CSS pixels per inchon this screen
 
Color depthbits per pixel
 
Orientationand touch
 

Screen is the whole display. Viewport is the part of the browser window that shows the page. Values marked "about" come from the estimate. Pixel density counts the pixels your computer draws. If your system scales the display, the panel's own pixel count can differ, and a browser cannot see it.

Bank card: 85.6 mm

Match your card

  1. Hold a bank card flat against the screen.
  2. Line up its left edge with the outline.
  3. Drag the grip on the right until the right edge matches.

Any card in the standard size works: credit, debit, driver's license, library or gift card. No card? Match a coin or a sheet of paper in the online ruler. This page reads that match too. Keep the browser zoom at 100 percent. The match is saved only in this browser.

What the checker shows when the page loads

The big number at the top is your screen diagonal in inches and cm. It is an estimate, and the page says so. The checker reads how many pixels your screen has and how many of them the browser packs into one CSS pixel. Then it looks for that pixel count in a built-in list of common iPhones, iPads, Android phones, MacBooks, Windows laptops and monitors.

Some pixel counts fit more than one size. A 1920 by 1080 screen can be a 24 inch monitor or a 15.6 inch laptop. The checker uses your pixel ratio and device type to pick the likelier one, and lists the others as "could also be". If your screen is not in the list, it uses the usual pixel density for that kind of device. It then tells you the guess is rough.

How to get the exact size with a card

  1. Press Measure with a card in the box next to the result (below it on a phone), or Measure at the top of the page on a wide screen.
  2. Hold a bank card flat against the screen, on the outline.
  3. Line up the left edges. Drag the grip until the right edge of the outline meets the right edge of the card. Use the 0.1 mm buttons for the last bit.
  4. Press My card matches. The big number now says Measured, and the estimate moves to the side box.

The match is saved in this browser for this screen. Come back later and the measured size is there. Plug in another monitor and it shows a new estimate, because each screen has its own pixel size. The page never opens the card match by itself.

Why an estimate can be wrong

A web page can read how many pixels your screen has. It cannot read how wide a pixel is. A 1920 by 1080 screen can be a 13 inch laptop or a 27 inch monitor. So any site that shows inches the moment it loads has to guess, from the resolution or a list of devices. Two such sites can give two different answers for the same screen.

A card fixes this. Every bank card is 85.6 mm wide. When the outline matches the card, the page knows how many pixels make a millimeter on your screen. Then the size is simple math: the pixels across divided by pixels per millimeter gives the width, and the same for the height. The diagonal comes from the width and height.

Worked example: a 15.6 inch laptop

A common laptop has a 1920 by 1080 screen. After a card match the checker finds about 5.56 pixels per millimeter. The width is 1920 / 5.56 = 345 mm (13.6 in). The height is 1080 / 5.56 = 194 mm (7.65 in). The diagonal is the square root of 13.6² + 7.65², which is 15.6 inches. The pixel density is 141 pixels per inch.

Common screen sizes

Sides are for the visible picture, long side first. Your screen is marked too: "Likely yours" for the estimate, "Closest to yours" after a card match.

Common screen sizes, long and short side
SizeLong × short side (in)Long × short side (cm)ShapeTypical use
Phones
5.4 in 4.9 × 2.3 12.5 × 5.7 19.5:9 Small phones
5.8 in 5.3 × 2.4 13.4 × 6.2 about 19.5:9 Older small phones
6.1 in 5.5 × 2.6 14.1 × 6.5 about 19.5:9 Most standard phones
6.3 in 5.7 × 2.6 14.5 × 6.7 about 19.5:9 Standard phones, newer models
6.5 in 5.9 × 2.7 15.0 × 6.9 about 19.5:9 Older large phones
6.7 in 6.1 × 2.8 15.4 × 7.1 about 19.5:9 Large phones
6.8 in 6.2 × 2.9 15.7 × 7.3 about 19.5:9 Large Android phones
6.9 in 6.3 × 2.9 15.9 × 7.3 about 19.5:9 The largest phones
Tablets
8.3 in 6.9 × 4.6 17.6 × 11.6 about 3:2 Small tablets
10.2 in 8.2 × 6.1 20.7 × 15.5 4:3 Older standard tablets
10.9 in 9.0 × 6.2 22.7 × 15.8 1.44:1 Standard tablets
11 in 9.1 × 6.2 23.0 × 15.9 1.45:1 11 in tablets
13 in 10.4 × 7.8 26.4 × 19.8 4:3 Large tablets (12.9 and 13 in)
Laptops
11.6 in 10.1 × 5.7 25.7 × 14.4 about 16:9 Small school laptops
13.3 in 11.3 × 7.0 28.6 × 17.9 16:10 Small laptops
13.6 in 11.4 × 7.4 29.0 × 18.8 1.54:1 13 in thin laptops
14 in 11.9 × 7.4 30.2 × 18.8 16:10 Everyday laptops
14.2 in 11.9 × 7.7 30.2 × 19.6 1.54:1 14 in pro laptops
15.3 in 12.8 × 8.3 32.6 × 21.1 1.55:1 15 in thin laptops
15.6 in 13.6 × 7.6 34.5 × 19.4 16:9 Most 15 in laptops
16 in 13.6 × 8.5 34.5 × 21.5 16:10 Large laptops
16.2 in 13.6 × 8.8 34.6 × 22.3 1.55:1 16 in pro laptops
17.3 in 15.1 × 8.5 38.3 × 21.5 16:9 Desktop replacement laptops
Monitors
21.5 in 18.7 × 10.5 47.6 × 26.8 16:9 Small monitors
23.8 in 20.7 × 11.7 52.7 × 29.6 16:9 Sold as 24 in
24.5 in 21.4 × 12.0 54.2 × 30.5 16:9 Gaming monitors, sold as 25 in
27 in 23.5 × 13.2 59.8 × 33.6 16:9 Common desk monitors
31.5 in 27.5 × 15.4 69.7 × 39.2 16:9 Sold as 32 in
34 in 31.4 × 13.1 79.7 × 33.3 about 21:9 Ultrawide
49 in 47.2 × 13.3 119.8 × 33.7 32:9 Super ultrawide

How to measure a screen by hand

Take a tape measure. Measure from the top left corner of the lit picture to the bottom right corner. Leave out the plastic or metal frame (the bezel). The number in inches is the screen size that shops use. For a curved monitor, let the tape follow the curve.

Where else to find the size

  • Mac: Apple menu, About This Mac. The model name often includes the size, such as "13-inch".
  • Windows: Settings, System, About shows the model. Search the model name to find its screen size. Settings, System, Display shows the resolution, not the size.
  • iPhone and iPad: Settings, General, About, Model Name.
  • Android: Settings, About phone, then search the model name.
  • Monitor: the label on the back. Two digits in the model name are often the size, for example 27 in a "U27" model.

Screen size, resolution and PPI

Screen size is the physical diagonal. Resolution is the pixel count, such as 2560 by 1440. Pixel density (PPI) is how many pixels fit in one inch. A 27 inch 1440p monitor has about 109 PPI. A 27 inch 4K monitor has about 163 PPI, so text looks sharper at the same size.

Phones and Macs draw more pixels than the page sees. A pixel ratio of 2 means each CSS pixel uses 2 by 2 device pixels. Windows display scaling of 125 or 150 percent does the same. The checker shows both numbers. If your system scales the display to a "looks like" size, the pixel density it shows is for the pixels your computer draws, which can differ from the panel's own count.

Already matched a card in our online ruler? This checker reads the same saved match, so your measured size shows at once.

Frequently asked questions

What size is my screen?

The checker shows an estimate the moment the page loads. It matches your screen pixels to common phones, tablets, laptops and monitors. For the exact size, press Measure with a card, hold any bank card flat on the screen, and drag the outline until it matches the card. The match takes about 20 seconds and is saved in your browser.

How does the checker know my screen size so fast?

It does not measure. It reads your screen width and height in pixels and the pixel ratio, then finds that pixel count in a built-in list of common devices, such as the iPhone 15 or a 15.6 inch 1080p laptop. When one pixel count fits several sizes, it shows the most common and lists the others as "could also be". The result is labeled Estimated.

How accurate is the estimate?

It is right for most phones, tablets and MacBooks, because each has a known pixel count. It is less sure for 1920 x 1080, which fits both laptops and monitors, and for screens not in the list, where it uses a typical pixel density and can be off by 10 to 20 percent. A card match gives the exact size, to about 0.1 inch.

Can a website detect my screen size in inches?

Not exactly. A browser tells a page how many pixels the screen has and the pixel ratio, but not how big a pixel is. Sites that print inches right away estimate from the resolution or from a list of devices, and two sites can give two different answers for the same screen. A card of known size gives the page the missing number, so the size becomes a measurement.

How do I measure my screen size by hand?

Use a tape measure from one corner of the visible picture to the opposite corner. Do not include the frame (bezel) around the screen. The result in inches is the screen size. For width and height, measure the visible area across and up.

Why does my 15.6 inch laptop measure 15.5 inches?

Makers round the size, and some screens have rounded corners that the sold size still counts. A card match by eye can also be off by a fraction of a millimeter. A gap of 0.1 to 0.2 inches is normal. The checker also shows the closest common size.

Is screen size the same as screen resolution?

No. Screen size is the physical diagonal, in inches or cm. Resolution is the number of pixels, for example 1920 x 1080. Two screens of the same size can have different resolutions. Pixel density (PPI) links the two: pixels along the diagonal divided by the diagonal in inches.

Which card can I use?

Any card in the standard ID-1 size: a credit card, debit card, driver's license, library card, gift card or hotel key card. They are all 85.6 by 53.98 mm. Business cards are a different size, so do not use one.

Does it work on a phone or tablet?

Yes. The estimate works at once on iPhone, iPad, Android phones and tablets. To measure with a card, the outline stands on its short side on a narrow screen, so the card fits. Keep the page at 100 percent zoom while you match the card. If you pinch to zoom, the outline is no longer true size and the checker warns you.

Do you save or send my measurements?

Nothing is sent. The estimate is worked out in your browser. The card match is saved only in this browser, one record per screen. The online ruler on this site reads the same record, so you match the card once for both tools. Clear your browser data or press Forget this screen to remove it.

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