Screen Resolution Test

What this screen resolution test shows

The resolution of a screen is the number of pixels it is made of, given as width × height: 1920 × 1080 means 1920 pixels across and 1080 down. More pixels on the same surface give a finer picture.

Asking a browser for this number is less simple than it seems. Most screens today are scaled: the system enlarges everything so that text stays readable, and tells websites about a smaller screen. This test reads what your browser reports, works out the real pixel count, and explains the difference:

• Your real resolution, with its common name (Full HD, QHD, 4K UHD…) and its aspect ratio.
• The size websites see, the scaling of your system, the size of the browser window and the usable area.
• A native-resolution check: test patches that show whether the picture reaches the screen pixel for pixel.
• The pixel density (PPI), computed from the diagonal you enter.

Nothing is installed, no permission is asked and nothing leaves your browser.

How to use it

1. Read the large figure at the top: it is the real pixel count of the screen that shows this window.
2. Check the list under it. The values follow you: resize the window, turn your phone, or drag the window to a second screen.
3. Look at the three test patches and answer the question below them. Do not scroll while you look.
4. Enter the diagonal of your screen, in inches or centimetres, to get its pixel density and physical size.
5. Copy all values for a support request, or save the result to compare two screens or send a link.

How to read your results

Screen resolution

This is the size websites see multiplied by the pixel ratio. A laptop that reports 1536 × 864 with a ratio of 1.25 has a 1920 × 1080 screen. When the scaling is not a round number, browsers round their figures, and the product can miss by a pixel: the test then brings it back to a resolution that screens are really built with. If none is close, the figure is shown with “about”.

Scaling

100% means that one pixel of a web page is one pixel of the screen. At 150%, each page pixel is drawn with one and a half screen pixels in each direction; at 200%, with two. Dense screens need scaling: without it, text on a 4K laptop would be tiny. Scaling does not reduce sharpness. The screen still uses all its pixels, and text is drawn more finely.

Browser window and usable area

The usable area is the screen without the task bar or the dock. The browser window is the part of the page you can see, without the tabs and the address bar. Web designers care about this last value: it decides which layout of a site you get.

Native resolution check

Every flat screen has one native resolution: its real grid of pixels. The three patches are drawn with lines and squares exactly one screen pixel wide.

• Even grey, or fine regular lines: each drawn pixel lands on one screen pixel. The screen runs at its native resolution.
• Wide bands, waves or coloured stripes: the picture is resized somewhere between the system and the panel. Fine lines cannot survive a resize, so they turn into visible patterns. Text and thin lines are slightly blurred for the same reason.

On a very dense screen you cannot tell the lines apart, and the patches look evenly grey: that is a correct result.

Pixel density

Density is the number of pixels per inch (PPI). It links the resolution to the physical size: 1920 × 1080 is coarse on a 32-inch monitor and very fine on a 6-inch phone.

Why a site shows a smaller resolution than the box

• Scaling. A 3840 × 2160 monitor at 200% tells websites that it is 1920 × 1080. Both figures are right: one counts screen pixels, the other the units websites work in.
• Phones and tablets. A phone with a 1179 × 2556 screen reports 393 × 852 and a pixel ratio of 3. All phones do this, so that websites keep a readable size.
• Browser zoom. Zooming a page changes the pixel ratio the page can read, and the computed resolution becomes wrong. The test warns you when it suspects this. Press Ctrl and 0 (Cmd and 0 on a Mac) to return to 100%.
• Privacy protection. Some browsers can report the size of the window in place of the screen, so that sites cannot recognise your device: Tor Browser does, and Firefox and Brave can, depending on their settings. The test tells you when the screen and the window have exactly the same size.
• A second screen. The values describe the screen that shows the browser window. Move the window to test the other one.

Common resolutions

Many laptops, tablets and phones use resolutions without a common name, such as 2880 × 1800 or 1179 × 2556. The test then gives the class they belong to.

How to change the resolution or the scaling

• Windows 11 and 10. Settings, System, Display. “Display resolution” should be the value marked “Recommended”: that is the native resolution. “Scale” changes the size of text and windows without leaving the native resolution.
• Mac. System Settings, Displays. “Default” suits the screen. The “Larger Text” and “More Space” choices are scaled modes: the picture is computed at another size, then fitted to the panel.
• Android. Settings, Display. Some phones offer “Screen resolution” (for example FHD+ or QHD+) to save battery, and “Display size” for scaling.
• iPhone and iPad. The resolution cannot be changed. Settings, Display & Brightness, “Display Zoom” enlarges everything.

Troubleshooting

The picture looks blurry

Run the native resolution check. If you see bands or waves, set the resolution marked “Recommended” in your display settings, and set the browser zoom to 100%. With an external monitor, use a digital cable (HDMI, DisplayPort or USB-C) and turn off any scaling option in the monitor’s own menu.

The resolution shown is not the one of my screen

Reset the browser zoom first. Then check that the window is on the right screen. If the value equals the window size, a privacy protection is probably hiding the screen: the test says so in “What this means”.

The recommended resolution is not offered

The graphics driver or the cable is the limit. Update the graphics driver and plug the monitor directly into the computer, without an adapter. Old cables and some docks cannot carry high resolutions.

The fine lines flicker when I scroll

That is normal: one-pixel lines shimmer while they move. Judge the patches when the page is still.

Frequently asked questions

Is anything recorded or sent to TestrHub?

No. The values are read by the page in your browser and never leave it. Saved results stay in your browser, and a result is only shared if you copy its link.

What is the difference between resolution and screen size?

The resolution counts pixels. The size, in inches, measures the diagonal of the panel. Two screens of the same size can have very different resolutions, and the pixel density tells them apart.

What is a pixel ratio?

It is the number of screen pixels used for one unit of a web page, in each direction. Websites call it the device pixel ratio. It is 1 on a classic monitor, 2 on most high-density laptops and 3 on many phones.

Is a higher density always better?

Up to a point. Beyond the density at which your eye can no longer see single pixels from your usual distance, more pixels bring nothing visible and cost battery and graphics power.

Why does the test say “about”?

With some scaling values the browser gives rounded figures, and the exact pixel count cannot be recovered. The value is then right to within a pixel or two.

Which test should I run next?

The refresh rate test measures how many pictures per second this screen shows, and the screen test checks it for uniformity, backlight bleed and banding.