What resolution is your screen really running?

Browsers report resolution in a way that confuses almost everyone: a 4K TV usually says 1920 x 1080. This test does the arithmetic properly, tells you the real pixel count, and shows a fine pattern that reveals whether the panel is genuinely resolving every pixel.

This test needs JavaScript to run. The explanation below still covers what the numbers mean, so the page is useful either way.

Reading your screen...

The numbers

Confirm the panel resolves it

The numbers above are what the browser reports. This pattern is a physical check: a one pixel checkerboard and fine line grid. On a screen genuinely resolving every pixel it looks like an even texture. If it shimmers, moires badly or turns into a flat grey, the image is being scaled somewhere.

Open the pixel pattern

What this test can and cannot tell you

Resolution is one of the most misreported numbers on the web. Here is what is real.

The reported resolution

Measured, but in CSS pixels. This is the coordinate space the browser lays out in. On a 4K TV it is usually 1920 x 1080 with a pixel ratio of 2, which is not the panel resolution.

The physical pixel count

Calculated, and this is the number that matters. Reported resolution multiplied by the pixel ratio. This normally matches the panel on a TV.

Whether the panel is truly 4K

The pattern helps, the numbers alone do not. A TV can report 4K while scaling the browser output. The fine pattern shows whether pixels are actually being resolved one to one.

Screen size in inches

Not knowable. A browser sees pixels, never a diagonal measurement. Nothing on the web can tell you your screen size.

The resolution of your video

Different question. This measures the screen. What resolution Netflix is actually sending you depends on your plan, the title and your connection.

Why a 4K TV says 1920 x 1080

CSS pixels are not panel pixels

Browsers work in a coordinate space designed so text stays a readable size on any screen. On a high density display, one CSS pixel covers several physical ones. The ratio between them is the device pixel ratio.

The arithmetic

Physical resolution equals reported resolution multiplied by pixel ratio. 1920 x 1080 at a ratio of 2 is 3840 x 2160, which is 4K. The test does this for you above.

Why TVs in particular do this

At three metres away, text rendered at true 4K density would be unreadably small. TV browsers therefore almost always run at a ratio of 2, presenting a 1080p coordinate space on a 4K panel. That is correct behavior, not a fault.

When the number really is wrong

If physical pixels come out at 1920 x 1080 on a TV you bought as 4K, either the browser is rendering at half resolution, or something in the chain is limiting it. The pattern check will usually make that obvious.

Questions people ask

Why does my 4K TV report 1920 x 1080?

Because browsers report resolution in CSS pixels, not physical pixels. Your TV is almost certainly running a pixel ratio of 2, so 1920 x 1080 multiplied by 2 gives 3840 x 2160, which is 4K. The Physical pixels row above does that multiplication for you.

How do I know if my TV is really 4K?

Check the physical pixel figure above first. Then open the pixel pattern: on a panel genuinely resolving every pixel it looks like an even fine texture. If it collapses into flat grey or shimmers heavily, something in the chain is scaling the image.

Does this tell me what resolution Netflix is streaming?

No, that is a different question. This measures your screen. What a streaming service actually sends depends on your subscription tier, the specific title, your connection speed and the app. Our capability test and speed test cover that side.

My monitor reports a different resolution than Windows says.

Browsers report the CSS pixel space, and Windows display scaling changes that. At 150% scaling a 2560 wide monitor reports about 1707 CSS pixels. Multiply by the pixel ratio and you should get back to the real number.

Can you tell me my screen size in inches?

No. No website can. A browser is told about pixels, never about physical dimensions. Screen size is on the box, the label on the back, or in the TV settings menu.