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Free Online Screen Test & Monitor Test

28 free display tests that run in your browser: dead pixels, backlight bleed, refresh rate, PWM flicker, HDR and more. Nothing to install, no account.

Start Dead Pixel TestBrowse all 28 tools

Quick full-screen colors

Tap a color to fill your screen instantly. Use ← / → to switch, Esc to exit.

Open color test →

Panel & Backlight

Dead Pixel TestFull-screen solid colors to find dead, stuck, and bright pixels.Open test→Backlight BleedReveal LCD backlight leakage and IPS glow in a dark room.Open test→Brightness UniformityA 50% gray field, a 9-zone grid and a panning gray to spot uneven backlighting.Open test→Blooming TestA bright object on black to judge local-dimming halos.Open test→Burn-in TestFull-screen fields and a checkerboard to reveal OLED burn-in.Open test→Contrast TestBlack-and-white checkerboards to judge black/white separation.Open test→Black Level TestNear-black steps to see how dark your panel really goes.Open test→Viewing Angle TestGrey steps and color bars to reveal off-axis color/brightness shift.Open test→Touch Screen TestTouch every cell or draw freely to find dead zones and multi-touch limits.Open test→Overscan TestEdge markers, circles and a grid to catch cropping, stretching and distortion.Open test→Sharpness TestPixel-level lines, checkerboards and text to expose scaling blur and oversharpening.Open test→PWM Flicker TestBright fields and a fast-moving line for the pencil and camera flicker tests.Open test→

Color & Calibration

Color TestDisplay pure black, white, red, green, blue and more, full-screen.Open test→Black ScreenA pure black full-screen for backlight, dust, and OLED checks.Open test→White ScreenA pure white full-screen for cleaning, lighting, and uniformity.Open test→Greyscale TestSmooth gradient and 32-step ramp to reveal color banding.Open test→Color GradientSmooth spectrum and RGB gradients to judge color transitions and banding.Open test→Gamma TestStripe-vs-patch pattern to read your display's gamma.Open test→Wide Color Gamut TestHidden logos in P3 colors that only a wide-gamut screen can show.Open test→HDR TestA real HDR image with brightness steps up to 1,600 nits, plus HDR detection.Open test→

Motion & Timing

Refresh RateMeasure your real refresh rate and watch a moving reference.Open test→Ghosting TestMoving boxes at selectable speeds to reveal ghosting and trails.Open test→Screen Tearing TestFast scrolling bars that reveal tearing without V-Sync/VRR.Open test→Frame Skipping TestOne cell per frame — photograph it to catch a screen that drops frames.Open test→

Fun & Utilities

Fake Broken ScreenCracked, glitch, TV static, no signal, dead pixels, glitching pixels, Windows BSOD, Mac, Linux, iOS and Android crash screens to prank friends.Open test→ScreensaverMatrix rain, starfield, snow, pipes, clock, and the classic DVD logo, full-screen.Open test→Boot Screen SimulatorFull-screen Windows 10, Windows XP, and macOS startup screens.Open test→Screen InfoSee your screen resolution, scaling, refresh rate, color gamut and HDR support.Open test→

What's wrong with my screen?

Find what you're seeing, run the matching screen test, then read what the result means.

A dot that stays one color

Run the Dead Pixel Test →Guide: Dead, stuck or hot?

Glow along the edges in a dark room

Run the Backlight Bleed Test →Guide: Bleed or IPS glow?

Patchy or uneven brightness

Run the Brightness Uniformity Test →Guide: Checking a TV for defects

A faint ghost of an old image on an OLED

Run the Burn-in Test →Guide: OLED burn-in

A 144 Hz monitor that feels like 60

Run the Refresh Rate Test →Guide: Enable full refresh rate

Smears trailing behind moving objects

Run the Ghosting Test →Guide: Fixing ghosting

The picture splitting sideways in games

Run the Screen Tearing Test →Guide: V-Sync, G-Sync, FreeSync

Tired eyes when the brightness is low

Run the PWM Flicker Test →Guide: PWM flicker

Halos around bright objects on black

Run the Blooming Test →Guide: Mini-LED vs OLED

Grey, washed-out blacks

Run the Black Level Test →Guide: Full vs limited RGB

Thin lines running across the screen

Run the Color Test →Guide: Lines on the screen

Stripes where a gradient should be smooth

Run the Greyscale & Banding Test →Guide: Color banding

Normal, or worth returning?

Most panels have small quirks. Here's how to tell them apart from real defects.

One dark (dead) pixelOften within the maker's allowanceCheck the pixel policy. Inside the return window you can usually just send it back. Pixel policies →
One bright or stuck pixelCounted more strictly than a dark oneTry the stuck-pixel fixer in the Dead Pixel Test, then check the policy. Fixing a stuck pixel →
Several faults close togetherClusters often qualify when scattered faults don'tPhotograph them on a solid color and count them by type.
A whole row or column lit or darkA connection fault, not a pixel defectThis almost always qualifies for service. Contact support.
Faint glow in the corners on a black screenNormal on nearly every LCDOnly worth returning if it's uneven or visible in everyday use. Backlight bleed →
A glow that moves when you move your headIPS glow, a trait of the panel typeNot a defect. Sitting further back or adding a little room light reduces it. IPS glow →
Corners a little darker than the centerSome falloff is normal on every LCDA distinct patch with a visible edge is not; that one is worth returning.
Blotches on a laptop screen, often in a linePressure marks, a mechanical faultWorth returning, especially on a new laptop.
An OLED outline that fades after varied contentTemporary image retentionPlay varied full-screen video for a while and check again.
An OLED outline that never fadesBurn-in, which is permanentCheck whether your warranty covers burn-in; some now do.
60 Hz on a 144 Hz monitorA setting or cable problem, not a faulty panelSelect the full rate in your display settings, check the cable, then test again.

Tests for newer screens

HDR, Mini-LED, OLED and high-refresh panels fail in ways a solid color can't show.

HDR Test

A real HDR image with brightness steps up to 1,600 nits, so you can see where your screen stops getting brighter.

PWM Flicker Test

Catch a flickering backlight with the pencil test, or a fast line that splits into copies on PWM-dimmed screens.

Wide Color Gamut (P3) Test

Logos hidden in Display P3 colors only appear if both your screen and your browser go beyond sRGB.

Frame Skipping Test

One cell lights per frame. Photograph it to find out whether an overclocked monitor quietly drops frames.

Blooming zone sweeps

Count how often the halo jumps as a square crosses the screen to estimate a Mini-LED's dimming zones.

Panning grey

Drifting grey bands that expose the dirty screen effect large TVs show when the camera pans.

Testing a specific device?

Step-by-step walkthroughs for laptops, phones, TVs and monitors.

Any new screen: the 10-minute checklist

Seven checks in order, from dead pixels and dark-screen defects through motion and viewing angle, and what counts as a defect.

Laptops

A 60-second pixel check, plus the things that look like dead pixels on a laptop but aren't, such as corner glow and lid pressure marks.

Secondhand phones

What to check before you hand over money: retained images on OLED, areas that ignore touch, a replacement panel, and flicker.

TVs

Get a test pattern up with the TV's browser or your phone, then judge pixels and uniformity from where you actually sit.

Monitors, in the store and at home

What you can check before paying, what to run on day one, and the red flags worth a return, the cable included.

Which panel type?

TN, IPS, VA and OLED compared on color, contrast, speed and viewing angle, with a pick for gaming, work and movies.

Before you test

A minute of setup makes every result easier to trust.

Let it warm up

A cold panel's brightness and color drift slightly at first. Give it about five minutes before testing, and 20–30 minutes before calibrating.

Switch off the filters

Night Light, Night Shift, True Tone, dynamic contrast and eye-care modes all change what you see. Turn them off for color and greyscale checks.

Dim the lights

Bleed, blooming and black-level tests need a properly dark room. Everything else works best dimly lit, with no reflections on the glass.

Use the native resolution

A scaled resolution softens fine detail and can blur a single bad pixel into its neighbors. Set your system to the panel's native resolution.

Fill the whole screen

Browser bars and the taskbar cover the edges, which is where bleed and dead pixels like to hide. Every test has a full-screen Start button.

Photograph what you find

Lock your phone camera's exposure, shoot in a dark room and note the date. That photo is your evidence for a return or warranty claim.

Questions

Is BestScreenTester free?

Yes. Every test is free to use, with no account and nothing to download. The site is supported by ads and donations.

Is anything uploaded when I run a test?

No. Your browser draws the test patterns on your own device, and nothing about your screen is sent anywhere. Like most websites, the site uses analytics and ads; the Privacy page lists what they collect.

Do the tests work on phones and tablets?

Yes, in any modern mobile browser. iPhone Safari doesn't let websites go truly full-screen, so there a test fills the browser window instead. The Touch Screen Test is built specifically for phones and tablets.

Can a browser test be accurate?

For defects you can see, yes: a full-screen solid color shows a dead pixel or backlight bleed just as clearly as dedicated software would. Measurements such as Delta E, brightness in nits or contrast ratio need a colorimeter; these tests show what those problems look like, not the numbers.

How many dead pixels are acceptable?

It depends on the manufacturer's pixel policy. One dark pixel often falls within the allowance, while bright pixels and clusters are treated more strictly. Inside the retailer's return window you usually don't need to argue about counts at all.

Which test should I run first on a new screen?

The Dead Pixel Test. Then check for bleed on black, uniformity on grey and banding in the gradients, and on a monitor or TV finish with the refresh rate. The new-device checklist in our guides walks through the full order.

Who makes BestScreenTester

BestScreenTester is built and maintained by Nelera, currently a one-person operation. Every guide shows when it was last updated, and many link the standards and manufacturer documents they draw on.

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