What is my screen resolution?

Reading your screen resolution

The big number at the top is your physical resolution — the number of pixels the panel really has, such as 1920 × 1080 or 2560 × 1440. It is worked out as screen.width × devicePixelRatio, then matched against a list of known panels so small rounding errors disappear and a common monitor, Surface, iPhone or iPad is named correctly. That product doesn't change when you zoom the page, and it isn't fooled by a browser side panel, Edge's sidebar or docked developer tools, which only make the viewport narrower.

One case needs care: Macs using a scaled “looks like” setting. macOS draws the desktop at twice the looks-like size and then resamples it to the panel, so the browser sees the drawn size, not the panel. The default on a 13.6-inch MacBook Air is “looks like 1470 × 956”, which renders 2940 × 1912 on a 2560 × 1664 panel. When the rendered size matches a known Mac scaled mode the tool shows the panel and says what macOS is rendering; where the same size could be native on one Mac and scaled on another, it labels the figure rendered and lets you pick your model.

Below the headline, three panels break down everything the browser knows:

• Screen — physical and CSS resolution, device pixel ratio, the space left after the taskbar or dock, aspect ratio, reported colour depth and orientation.
• Browser window & zoom — the viewport a page actually gets, the visible area after pinch-zoom or an on-screen keyboard, the window's size and position, and the scale factor.
• Capabilities — an estimated refresh rate, colour gamut, HDR, multiple screens, touch support and pointer type.

Everything updates live. Resize the window, rotate your phone, drag the browser to another monitor or press Ctrl + and the changed values flash. In Chrome and Edge, Show all screens lists every connected monitor with its own resolution, scaling and position.

Physical pixels, CSS pixels and device pixel ratio

Modern screens are too dense to show web pages at one pixel per pixel — text would be microscopic on a phone. So browsers work in CSS pixels, and the device pixel ratio (DPR) says how many real pixels make up one CSS pixel in each direction.

On a desktop the DPR is the product of two settings: display scaling in Windows Settings or macOS Displays, and the browser's page zoom (Safari is the exception — its zoom leaves DPR alone). No browser reports those two separately on an ordinary page, so the tool shows the combined scale factor and tells you whether the value is a standard scaling step. A DPR of 1.25 could be 125% scaling or 125% zoom; a DPR of 1.1 isn't a Windows scaling step, so zoom is almost certainly involved. Some sites guess zoom by comparing the window's outer width with the viewport, but a side panel or docked dev tools makes that comparison look like zoom, so we don't. In Chrome and Edge, Show all screens asks for permission to read each screen's own scale factor, which splits the two exactly.

Developers: media queries and window.innerWidth use CSS pixels, so the viewport figure and the Tailwind or Bootstrap breakpoint shown are the ones your layout responds to.

Working out PPI and pixel pitch

No browser can tell how big your screen physically is, so pixel density needs one fact from you: the diagonal. Choose a common size or type your own — 27, 15.6", 27”, 27 in. or 68.6 cm all work — and the calculator gives:

• Pixels per inch (PPI) — the diagonal pixel count divided by the diagonal length. Around 90–110 is typical for desktop monitors, 140–220 for sharp laptop screens, and 400 or more for phones.
• Pixel pitch — the distance between pixel centres in millimetres, the figure monitor spec sheets quote.
• Visible width × height — handy for checking a monitor will fit a desk or a TV a wall.
• Distance where pixels vanish — beyond this, someone with normal vision (one arc-minute of acuity) can no longer pick out individual pixels. Sit closer and a higher resolution is a visible upgrade; sit further back and it isn't.

The calculator uses the panel resolution from the top of the page. If you're on a Mac whose rendered size matches more than one model, pick yours in the explanation or type the panel's native resolution into the override box for an exact PPI. To measure real-world sizes on screen, calibrate the online ruler.

Which resolution is right for what

For a monitor, resolution only makes sense together with size and viewing distance. 1080p is sharp at 24 inches and looks soft at 27. 1440p is the sweet spot for 27-inch gaming and office monitors, at about 109 PPI with no scaling needed. 4K at 27 inches is 163 PPI and wants 150% scaling for readable text, but everything becomes crisply printed-looking; at 32 inches it works at 125%. Ultrawide 3440 × 1440 is a 1440p screen stretched to 21:9 for games and timelines.

On laptops, a high-DPI panel with scaling looks sharper than a native low-resolution one, at a small cost in battery life. If you use a TV as a monitor, check the chroma subsampling pattern: smeared red-on-blue text means the TV is throwing away colour detail, which a PC or Game mode usually fixes. For games, the GPU has to render every physical pixel, so a 4K screen needs roughly two and a quarter times the graphics power of 1440p for the same frame rate — check what your display can actually show with the refresh rate test, and look over a new panel with the dead pixel test.

Frequently asked questions