Screen tests, calculators, and foldable display checks

Screen tests, calculators, and foldable display checks is the tool on this page. The control sits above this text. Use it on the display you want to judge, then read what the result can and cannot mean. The target phrase people search is tied to this job, and the explanation below stays with that job instead of repeating a generic review of every display ever made.

The useful order is simple. Look at the panel with a flat color before you trust a spec sheet. Then calculate the density and the physical size. Then compare two resolutions at the size you will actually sit in front of. Screenz is arranged that way: screen tests, calculators, comparisons, visualizers, and a short set of guides for refresh, scaling, distance, HDR, and response time. Foldable phones have their own pages because a Galaxy Z Fold, a Galaxy Z Flip, and an iPhone Duo are two displays in one object.

A 27-inch 2560×1440 monitor is about 109 pixels per inch. A 6.1-inch phone near 1179×2556 is past 450. The same word, resolution, means a sharp phone and a merely fine desktop. That is why a PPI calculator sits next to the dead-pixel test instead of in a separate hobby site. You find a mark, then you learn whether the mark is large because the pixels are large.

Comparison pages are not a ladder where 8K always wins. At a desk, 4K on 27 inches with ordinary scaling can make text smaller than you want, while 1440p at the same size is dense enough and lighter on a graphics card. On a sofa, 720p on a 65-inch television is soft and 4K is the picture the set was built to show. The pages say that with the pixel counts beside a scaled rectangle, not with a trophy.

Foldable pages use published figures and label them. The Galaxy Z Fold 7 inner display is 8.0 inches at 1968×2184, about 368 PPI, and the cover is 6.5 inches at 1080×2520, about 422 PPI, both listed at 120 Hz. The Galaxy Z Flip 7 main display is 6.9 inches at 1080×2520 and the cover is about 4.1 inches. iPhone Duo, the phone people still search for as iPhone Fold, is described in launch coverage as a 7.6-inch inner display and a 5.4-inch cover. Confirm those numbers on the maker's page before you argue with a shop. Use them here to see how different the two faces are, then run the dead-pixel and uniformity tests on each face.

If you only open one tool, open the dead-pixel test, go fullscreen, and walk red, green, blue, white, and black. If the panel is clean and you came for a purchase, open the PPI calculator and the viewing-distance guide. If you are setting up a game, open refresh rate, frame time, and the settings note. The rest of the site is the same habit: the tool first, then a plain explanation of what the picture can and cannot prove.

Screenz is a set of pictures and arithmetic for the display you already have. The picture is drawn by the browser. The arithmetic is the same formula a spec sheet uses, written out so you can change the inputs. Neither one is a laboratory certificate. A dead pixel you can see is real. A refresh number that does not match the sticker is a clue about the operating system, the cable, the battery mode, or the browser, not an automatic failure of the panel.

Use fullscreen when you are hunting a mark. The address bar, the notch, and the rounded corner all hide the edge, and the edge is where a bad pixel and a fold crease like to sit. On a phone, turn the brightness up and turn off the reading tint. On a monitor, leave the preset you actually use, then repeat the test in the neutral preset if you are judging color. Night shift, f.lux, and vivid modes are fine for the evening and misleading for a test.

Dust sits on the glass and moves when you tilt the panel. A dead subpixel stays dark. A stuck subpixel stays lit, so it shows on black. A crease on a foldable is a hinge in the stack. It is not a dead pixel, and a flat color shows it more honestly than a photograph. Pressure spots and backlight bleed on an LCD change with the angle of your head. OLED black should look off, except at the camera hole and along a fold.

The browser cannot measure nits, cannot read EDID on most pages, and cannot promise that a 10-bit ramp is being sent as 10-bit. If a gradient shows steps, the steps may be the panel, the operating system, or the compositor. If a refresh counter reads 60 on a 144 Hz monitor, check the cable, the power plan, and the display setting before you blame the page. Screenz will say this again because it is the difference between a useful test and a false warranty claim.

Photographing the panel with a second phone adds moiré and makes uniformity look worse than it is. Trust your eye at the distance you actually sit. Move closer only to confirm that a mark is in the pixels rather than on the glass. Then wipe the glass and look again. A foldable should be checked twice, cover display and inner display, because they are different diagonals, different pixel densities, and often different aspect ratios.