Dead Pixel Test & Screen Resolution Checker
See your screen resolution, device pixel ratio and browser window size at a glance. Then start the dead pixel test, which fills your whole screen with red, green, blue, white and black, one color at a time, so that you can look for dots that do not match the rest. Free, no signup, and it runs in your browser.
The tool does not find faulty pixels by itself and it does not repair them. You look at the screen and judge what you see.
🧪 Dead Pixel Test (Monitor / Laptop Test)
Bought a new monitor or laptop? Use fullscreen solid colors to check for dead pixels, stuck pixels, and dust.
🔍 You Can Also Visit More Tools Categories
What is a Dead Pixel Test and Screen Resolution Checker?
Every screen is made of a grid of tiny dots called pixels. A screen resolution checker tells you how many pixels your screen has across and down, for example 1920 by 1080, and how your browser maps them. A dead pixel test helps you find pixels that do not work properly, such as a dot that stays black or stays bright on one spot.
Both are most useful when you have just bought a monitor, a laptop, a phone or a tablet, or when a screen has started to show a strange dot.
How to Check Your Screen Resolution
- Open this page and look at the first section.
- Read the Current Resolution. It is the width and height of your screen in pixels, as your browser reports them.
- Read the Device Pixel Ratio and the Browser Window Size, which are explained below.
- Click Copy Resolution if you want to paste the numbers into a message, a support form or a document.
How to Run the Dead Pixel Test
- Clean the screen with a soft, dry microfiber cloth, following the maker's advice. Dust and smudges can look like faulty pixels.
- Dim the room lights, and turn off night light, blue light or color filters, because they change the colors on the screen.
- Click Start Dead Pixel Test. The screen goes fullscreen and fills with the first color.
- Look closely at the whole screen, from one edge to the other, including the corners.
- Click anywhere, or use the Next button, to move to the next color: red, green, blue, white and then black.
- Press Esc to leave the test.
Note the color and the position of any dot that does not match the rest, and check it again on the other colors.
What You See on the Page
| Item | Meaning |
|---|---|
| Current Resolution | The width and height of your screen in pixels, as reported by your browser |
| Device Pixel Ratio | How many real screen pixels are used for each pixel of a web page |
| Browser Window Size | The width and height of the area where this page is shown |
| Copy Resolution | Copies the resolution so that you can paste it somewhere |
| Start Dead Pixel Test | Opens the fullscreen test |
| Test colors | Red, green, blue, white and black, one at a time |
| Click or Next | Changes to the next color |
| Esc | Leaves the test |
| Hint on the test screen | "Click anywhere to change color, Press ESC to exit" |
Understanding the Numbers
Screen resolution
The resolution is the number of pixels across (width) by the number of pixels down (height). More pixels means a sharper picture at the same screen size. The total number of pixels is the width multiplied by the height.
| Common name | Resolution | Total pixels | Shape (aspect ratio) |
|---|---|---|---|
| HD (720p) | 1280 x 720 | 921,600 | 16:9 |
| Full HD (1080p) | 1920 x 1080 | 2,073,600 | 16:9 |
| QHD (1440p) | 2560 x 1440 | 3,686,400 | 16:9 |
| 4K UHD | 3840 x 2160 | 8,294,400 | 16:9 |
To find the shape of your screen, divide the width and the height by their largest common number. For 1920 by 1080, that number is 120, which gives 16 by 9.
Device pixel ratio
A web page is measured in CSS pixels. The device pixel ratio says how many real pixels of the screen are used for each CSS pixel. A ratio of 1 means one to one. A ratio of 2 means that each CSS pixel is drawn with a block of 2 by 2 real pixels, which makes text and pictures look sharper. Many phones and high-resolution laptop screens use 2 or 3.
Browser window size
This is the width and height of the area where the page is shown. It is smaller than the screen when the window is not maximized, and it leaves out the tabs, the address bar and the toolbars of the browser, and the taskbar or dock. It changes when you resize the window, zoom, or rotate a phone.
Why the Resolution May Differ From Your Screen's Native Resolution
The resolution shown is what your browser reports, and it is measured in CSS pixels. Three things can make it differ from the real number of pixels on the panel:
- Display scaling: Operating systems let you make everything bigger, for example 125, 150 or 200 percent. The browser then reports a smaller resolution and a higher pixel ratio.
- Browser zoom: Zooming the page changes the pixel ratio and the window size.
- More than one screen: The numbers are normally for the screen where the browser window is, so the values can change when you move the window to another screen.
| Real screen | Scaling | Reported resolution | Device pixel ratio |
|---|---|---|---|
| 1920 x 1080 | 100% | 1920 x 1080 | 1 |
| 1920 x 1080 | 150% | 1280 x 720 | 1.5 |
| 1920 x 1080 | 200% | 960 x 540 | 2 |
| 3840 x 2160 | 150% | 2560 x 1440 | 1.5 |
| 3840 x 2160 | 200% | 1920 x 1080 | 2 |
To estimate the real pixels, multiply the reported width and height by the device pixel ratio. For example, a phone that reports 390 x 844 with a pixel ratio of 3 has about 1170 x 2532 real pixels (an example, not a specific phone). For the exact native resolution, check your operating system's display settings or the specification sheet of your screen.
What Are Dead, Stuck and Hot Pixels?
Each pixel is made of three tiny parts called subpixels, which are red, green and blue. A 1920 by 1080 screen has 2,073,600 pixels, which is 6,220,800 subpixels. Mixing the three at different strengths gives every color. A fault in one pixel or one subpixel shows as a small dot that does not change like its neighbors.
| Type | What happens | How it looks | Easiest to see on |
|---|---|---|---|
| Dead pixel | All three subpixels are off all the time | A black dot | White and other bright colors |
| Stuck pixel | One or two subpixels are on all the time | A red, green, blue or other colored dot | Black, and colors that differ from the stuck color |
| Hot or bright pixel | All three subpixels are on all the time | A white dot | Black |
People use these names in slightly different ways, so other sources may name them differently. What matters is the color of the dot and where it is.
What Each Test Color Shows
| Color | What to look for |
|---|---|
| Red | Black dots, or dots that are not red |
| Green | Black dots, or dots that are not green |
| Blue | Black dots, or dots that are not blue |
| White | Dark or colored dots. Also dirt, an uneven brightness or a color tint |
| Black | Bright dots (white or colored). Also glow along the edges or corners |
A pixel that looks normal on one color can show a fault on another, which is why the test goes through all five.
Other Things You May Notice
A solid color screen can show other issues too. They are not the same as a faulty pixel, and whether they count as a fault depends on the maker.
| What you see | What it usually is |
|---|---|
| Light leaking along the edges or corners of a black screen | Backlight bleed on screens with a backlight |
| A soft glow in the corners of a dark screen when you look from an angle | Often called IPS glow on screens with that panel type |
| A yellow, blue or pink tint, or patches of different brightness on white | Uneven brightness or tint |
| A fuzzy spot or a line that moves when you wipe the screen | Dust, a smudge or a hair |
| A faint trace of an earlier picture | Image retention, which can happen on some screen types after a still image has been shown for a long time |
Tips for an Accurate Test
- Clean the screen first. Use a soft, dry microfiber cloth, and follow the maker's advice for cleaning.
- Test in a dim room. Faults are easier to see when there is no glare.
- Turn off color filters. Night light, blue light filters, True Tone-style features and similar settings change the colors.
- Set the screen to a normal brightness. Very low brightness can hide a dot, and very high brightness can tire your eyes.
- Look from close and from a normal distance. A dot that you only see with your nose to the glass may not matter in daily use, but note it anyway.
- Scan every part of the screen, including the corners and the edges.
- Check each color for a few moments, and do not rush past the black and the white screens.
- Move your head slightly. A mark on the glass changes with the angle, and a pixel fault stays in the same spot of the picture.
- Test every screen of a set-up by moving the browser window to each monitor.
Found a Bad Pixel? What to Do
- Make sure that it is not dirt. Clean the screen and look again at the same spot.
- Note the color and the position, and take a clear photo if you can.
- Check the return period and the maker's pixel policy. Many makers say how many faulty pixels they accept, and the rules differ between makers, models and countries.
- Contact the seller or the maker early, especially if the screen is new.
- Do not press hard on the screen or use sharp objects. You can damage the display and may lose your warranty.
A stuck pixel sometimes becomes normal again after some time, but nothing guarantees it. This tool does not offer a pixel fixer and does not use flashing patterns, which can be uncomfortable to look at.
Buying a New Monitor, Laptop, Phone or Tablet
- Test the screen as soon as you unbox it, while you can still return or exchange it.
- Keep the box, the receipt and the packaging until you are sure that the screen is fine.
- Check the resolution against the specification that was advertised. Remember that scaling and zoom can change what the browser reports.
- Run all five colors and scan every part of the screen.
- Look at the settings of the device for resolution and scaling if the numbers surprise you.
- Read the pixel policy and the warranty terms before you decide to keep it.
Fullscreen Mode and the Esc Key
- Start: Click Start Dead Pixel Test. The browser asks to go fullscreen and fills the whole screen with one color.
- Change the color: Click anywhere, or use the Next button.
- Exit: Press Esc. This is a feature of the browser, and it always works to leave fullscreen.
- A hint is shown for a short moment: "Click anywhere to change color, Press ESC to exit". It fades away so that it does not look like a flaw on the screen.
- Phones and tablets: Some of them do not allow web pages to go fullscreen. The test then fills the browser window instead, and the browser bars can use some space at the edges.
Common Mistakes
- Blaming dust for a real fault, or a fault for dust: Clean the screen and look again at the same spot.
- Testing with a color filter or night mode on: The colors are then wrong.
- Testing in a bright room: Glare hides small dots.
- Reading the resolution as the exact native resolution: Scaling and zoom change what the browser reports.
- Testing only one color: Some faults show on one color only.
- Waiting too long: Return periods can be short, so test a new screen early.
- Pressing on the screen to fix a pixel: This can damage the display.
Good to Know
- The numbers come from your browser and describe the screen where this page is open.
- The browser window size and the pixel ratio change when you zoom, resize the window or rotate a phone.
- The tool cannot know the physical size of your screen in inches, so it cannot show the pixel density.
- The tool does not detect faults. You decide what you see.
- A brief test is safe. Avoid leaving a bright solid color on screen for a long time.
Privacy
- The numbers on this page come from your browser and are shown only to you. They are not sent to our server.
- The test runs in your browser, and nothing about your screen is saved.
- No signup, no account and no app install are needed.
Frequently Asked Questions
How do I check my screen resolution?
Open this page and look at the Current Resolution in the first section. It shows the width and height of your screen in pixels, for example 1920 x 1080, together with the device pixel ratio and the size of your browser window. Click Copy Resolution to copy the numbers.
Is the resolution shown the same as my screen's native resolution?
Not always. The browser reports the screen size in CSS pixels, and display scaling in your operating system and zoom in your browser can change that number. For example, a 1920 x 1080 screen set to 150 percent scaling is reported as about 1280 x 720 with a pixel ratio of 1.5. Multiplying the resolution by the pixel ratio gives a good estimate of the real pixels. For the exact native resolution, check your operating system's display settings or the specifications of your screen.
What is device pixel ratio?
Device pixel ratio is the number of real screen pixels that are used for each CSS pixel of a web page. A ratio of 1 means one to one. Many phones and high-resolution laptop screens use 2 or 3, which makes text and images look sharper. Browser zoom and display scaling change the ratio.
Why is my browser window size smaller than my screen resolution?
The browser window size is the area where the page is shown. It is smaller than the screen when the window is not maximized, and it leaves out the tabs, the address bar and the toolbars of the browser, and the taskbar or dock. It also changes when you resize the window, zoom in or out, or rotate a phone.
How do I run a dead pixel test?
Clean your screen, dim the room lights and click Start Dead Pixel Test. The screen fills with one solid color at a time: red, green, blue, white and black. Click anywhere or use the Next button to change the color, and press Esc to leave fullscreen. Look closely at every part of the screen on each color, and note any dot that does not match the rest.
Why does the test use these colors?
Different colors show different kinds of faults. A dot that stays dark on a white screen is a dead pixel. A dot that stays bright on a black screen is a stuck or bright pixel. On red, green and blue screens, a pixel whose red, green or blue part is stuck on or off shows up as a dot of another color. Checking all five colors catches more problems than checking only one.
What is the difference between a dead pixel, a stuck pixel and a hot pixel?
Every pixel is made of three tiny parts called subpixels: red, green and blue. A dead pixel is off all the time and shows as a black dot. A stuck pixel has one or two subpixels that are always on, so it shows as a red, green, blue or other colored dot. A hot or bright pixel is on all the time and shows as a white dot, which is easiest to see on a black screen. People use these names in slightly different ways, so other sources may use them differently.
How can I tell a dead pixel from dust or dirt?
Dust, a smudge or a hair on the screen can look like a pixel defect. Clean the screen with a soft, dry microfiber cloth first, following the maker's advice, and look again. A real pixel defect stays in exactly the same spot of the panel and keeps the same shape and color, while dirt can be wiped away or looks fuzzy and uneven. Do not press hard on the screen.
Can a dead or stuck pixel be fixed?
Sometimes a stuck pixel becomes normal again by itself over time, but there is no guaranteed fix. A pixel that is completely dead is a hardware fault in the panel. Be careful with advice that tells you to press on the screen or to use sharp objects, because it can damage the display. This tool only helps you find the problem. It does not repair pixels, and it does not use flashing patterns.
Does the warranty cover dead pixels?
It depends on the maker and the seller. Many makers have a pixel policy that sets how many faulty pixels, and of what kind, are accepted before a screen counts as defective, and some screens are covered only above that number. Check the policy and the return period of your screen as soon as you buy it, and test it early. Note the color and the position of each faulty pixel and, if you can, take a clear photo.
How do I exit the fullscreen test?
Press the Esc key. Your browser leaves fullscreen and returns to the page. On a phone or tablet without a keyboard, use the close option shown on the test screen or your device's own way to leave fullscreen.
Does it work on phones and tablets?
Yes, the page is designed for phone screens. Some phones and browsers do not allow web pages to go fullscreen. In that case the test fills the browser window instead, and the browser bars can take up a little space at the edges. The numbers in the first section change when you rotate the device, because the width and the height swap.
Is the test safe for my screen?
A short test is fine for normal screens. Avoid leaving a bright single color on the screen for a long time, especially on OLED and similar screens, where a still image shown for a long time can leave a faint trace. The colors change only when you click, and the tool does not flash. Bright full-screen colors can be uncomfortable, so look away or stop if you feel any discomfort.
Does the tool find dead pixels by itself?
No. A web page cannot see the hardware faults of your screen. The tool fills the screen with clean colors, and you look for defects with your own eyes.
Is my information sent to a server?
No. The numbers come from your browser and are shown only to you. The test runs in your browser, and nothing is sent to our server.
Is this dead pixel test and resolution checker free?
Yes. The tool is free and needs no signup.