What Is My Screen Resolution?

Your screen resolution is the Real pixels figure below, read from this device.

Pattern Pick one, then go full screen.

What to look for

F goes full screen. Escape leaves.

Waiting for your browser

Reported size
Pixel ratio
Real pixels
Scaling

A page sees the signal the computer sends, not the panel. The patterns below show the rest.

Top and left rulers, a number every 200 pixels

Top and left rulers, a number every 200 pixels

Preview · enlarged so the lines show · full screen only

Rulers along the top and left edges count real pixels: a small mark every 20, a long one every 200, numbered where it fits. Full screen writes the size across the middle, and the last long mark plus the pixels beyond agree with it: 1,800 and 120 at 1,920 wide.

1 of 4

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More options

What to look for

Readings for common screens

Aspect ratios and the sizes that have them

Why the reading is not the number on the box

Next step Next: check that every pixel lights

How it works

What is my screen resolution? Your browser reports a size in CSS pixels and a pixel ratio; multiplied together they give your real pixels. This screen resolution test is a monitor resolution test on a desktop, and reads phones too.

Read the full guide

How to check monitor resolution, step by step

1. Set browser zoom to 100 percent, because zoom changes the pixel ratio. 2. Read Real pixels: the resolution your computer is sending to this screen. 3. Press Go full screen. On the ruler, the last long mark plus the pixels beyond it should agree with that figure.

A screen size test and a screen ratio test

Size here means pixels, not inches. Ratio has two meanings and both are here. The pixel ratio is one of the four numbers, and the aspect ratio is listed for each reading, such as 16:9 for 1920 by 1080.

Questions and answers

What resolution is my monitor?

The Real pixels figure, for the monitor this window is on. 1920 by 1080 is Full HD, 2560 by 1440 is QHD and 3840 by 2160 is 4K UHD. With two monitors, drag the window across and the figure can change.

Why is my resolution lower than the box says?

Often display scaling. At 125 percent a 1920 by 1080 screen reports 1536 by 864 with a pixel ratio of 1.25. Multiply the two and the full count comes back, which is what Real pixels shows.

Is my screen resolution the same as my screen size?

No. Resolution counts pixels; size is the glass, usually given as its diagonal in inches. A browser reports pixels and a pixel ratio and never the physical size, so no web page can work out inches or pixels per inch.

What aspect ratio is my screen?

Divide the real width by the real height. 1920 by 1080 and 2560 by 1440 are 16:9, 1920 by 1200 and 2560 by 1600 are 16:10, and 3440 by 1440 is sold as 21:9.

All 24 patterns and readings

Edge and ruler patterns 4

  • Crop frame at 2.5 and 5 percent in from the edge An outer line on the edge of the picture and two inner frames, 2.5 and 5 percent in from each side. On a TV that crops the picture, the outer line disappears and the inner frames show how much has gone.
  • Screen pixels beside CSS pixels Two grids of one-pixel lines. The left is counted in the screen's own pixels, the right in CSS pixels, the unit the reported size uses. At a pixel ratio of 1 they match. At 1.25 or 1.5 the right grid goes uneven, which is scaling made visible.
  • Top and left rulers, a number every 200 pixels Rulers along the top and left edges count real pixels: a small mark every 20, a long one every 200, numbered where it fits. Full screen writes the size across the middle, and the last long mark plus the pixels beyond agree with it: 1,800 and 120 at 1,920 wide.
  • Two-pixel line round the screen edge A white outline two pixels thick hugs the outside of the picture, with a cross marking the middle. Top, bottom, left and right should look equally thick. If one is thinner or absent, the picture is being cropped or resized on its way to the glass.
Show all 24 patterns and readings (20 more)

Readings for common screens 10

  • 1366 by 768 at a pixel ratio of 1 A widescreen size with 768 lines, 1,049,088 pixels in all. An exact 16:9 picture that tall would be 1365 and a third pixels wide, so the width was rounded up: the true ratio is 683:384. Reported size and real pixels match.
  • 1920 by 1080 at 100 percent Full HD with no scaling: the browser reports 1920 by 1080, the pixel ratio is 1 and real pixels read the same, 2,073,600 in all. The aspect ratio is 16:9. The long marks end at 1,800 across and 1,000 down.
  • 1920 by 1080 at 125 percent: reported as 1536 by 864 Scaling one step up. The pixel ratio is 1.25 and the browser is told 1536 by 864. Multiply back and the full 1920 by 1080 returns. Still 16:9, still 2,073,600 pixels: only the layout units changed.
  • 1920 by 1080 at 150 percent: reported as 1280 by 720 A pixel ratio of 1.5 on a Full HD panel makes the browser report 1280 by 720, the size of an HD screen. Real pixels still read 1920 by 1080. The reported size alone would undercount the screen by more than half.
  • 1920 by 1200 at 100 percent The 16:10 relative of Full HD, 120 pixels taller: 2,304,000 pixels, exact ratio 8:5. Reported size and real pixels match at a pixel ratio of 1. The long marks end at 1,800 across and 1,000 down, with 200 pixels below the last.
  • 2560 by 1440 at 100 percent QHD: 3,686,400 pixels, 16:9. At a pixel ratio of 1 the browser reports the full size. A 4K screen scaled to 150 percent reports these same numbers, and only its pixel ratio of 1.5 tells them apart.
  • 2560 by 1600 at a pixel ratio of 2: reported as 1280 by 800 A high-density laptop screen. Each CSS pixel is a block of four real ones, so the browser reports 1280 by 800 while 4,096,000 pixels are in use. The aspect ratio is 16:10, written 8:5 in lowest terms.
  • 2880 by 1800 at a pixel ratio of 2: reported as 1440 by 900 The same doubling on a larger panel: reported 1440 by 900, real 2880 by 1800, 5,184,000 pixels, 16:10. If real pixels read higher than the panel has, the computer is drawing a larger picture and shrinking it to fit.
  • 3440 by 1440: an ultrawide Sold as 21:9. The exact ratio is 43:18, about 2.39 to 1, a little wider than 21:9, which is 2.33. 4,953,600 pixels. The long marks end at 3,400 across with 40 pixels beyond.
  • A phone that reports 390 by 844 at a ratio of 3 This phone packs three real pixels into each CSS pixel in both directions, so 390 by 844 means 1170 by 2532 real pixels, 2,962,440 in all. Held upright the ratio is 195:422, about 9 to 19.5.

Aspect ratios and the sizes that have them 5

  • 3:2, between the two 2160 by 1440, 2256 by 1504 and 3000 by 2000. Width is 1.5 times height, taller than 16:10. Some notebook and tablet screens use it.
  • 4:3, the older monitor shape 1024 by 768, 1400 by 1050, 1600 by 1200 and 2048 by 1536. Width is 1.33 times height. It was the common shape of older tube televisions and monitors, before widescreen took over.
  • 16:9, the widescreen standard 1280 by 720, 1600 by 900, 1920 by 1080, 2560 by 1440 and 3840 by 2160 all divide down to exactly 16:9. Width is 1.78 times height. 1366 by 768 is sold as 16:9 and misses it by a fraction.
  • 16:10, a little taller 1280 by 800, 1440 by 900, 1680 by 1050, 1920 by 1200, 2560 by 1600 and 2880 by 1800. In lowest terms the ratio is 8:5, and width is 1.6 times height: a ninth more height than 16:9 at the same width.
  • 21:9, the ultrawide label No common screen is exactly 21:9. 2560 by 1080 is 64:27, about 2.37 to 1, and 3440 by 1440 is 43:18, about 2.39 to 1. Both are sold as 21:9 so they can be compared with 16:9 at a glance.

Why the reading is not the number on the box 5

  • A TV that crops the edges A TV can enlarge the picture slightly and cut off its edges, which is called overscan. The numbers still show what the computer sends. Only the patterns reveal it: the edge border loses a side and the frame shows how far in the cut is.
  • Browser zoom changes the pixel ratio too Zooming a page to 110 percent raises the ratio the browser reports, exactly as scaling does, and the page cannot tell the two apart. Set zoom back to 100 percent and the four numbers update by themselves. Pinch zoom leaves the ratio alone.
  • Display scaling shrinks the reported size The operating system enlarges text by raising the pixel ratio, and the browser is told a smaller screen to match. Real pixels multiplies the two back together. A reported size below the number on the box, with a ratio above 1, is scaling and not a fault.
  • No browser can read inches A page is told pixels and a pixel ratio, never the size of the glass. So this is a size in pixels. Inches, and pixels per inch, need something of known length held against the screen, which a web page does not have.
  • The numbers belong to the screen this window is on With two displays, the browser reports the one that holds the window. Drag the window across and the size and the pixel ratio can both change, since each display has its own resolution and scaling.

How this list was compiled: Written for this page. Every scaled size, pixel count and aspect ratio was computed: the size a browser reports is the real size divided by the pixel ratio, and an aspect ratio is width and height divided by their largest common factor. That a browser reports the screen's width and height in CSS pixels is from https://developer.mozilla.org/en-US/docs/Web/API/Screen/width and https://developer.mozilla.org/en-US/docs/Web/API/Screen/height. That the pixel ratio is the ratio of physical pixels to CSS pixels, that page zoom changes it while pinch zoom does not, that 2 is expected on high-density screens and more on many phones, and that it can change when a window is dragged to another display, is from https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio. The names and sizes of the resolutions, and that 2560 by 1080 and 3440 by 1440 are sold as 21:9 while being 64:27 and 43:18, are from https://en.wikipedia.org/wiki/Display_resolution_standards and https://en.wikipedia.org/wiki/List_of_common_display_resolutions. Overscan is from https://en.wikipedia.org/wiki/Overscan. All read 2026-10-02. A web page sees what the computer sends, never the panel itself, and it is told nothing about the size of the glass. Licence: own work

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