How many dead pixels are acceptable?
Manufacturers allow a surprising number of defective pixels before a panel counts as faulty. Here are the actual ISO thresholds by resolution.
Most people are surprised by this: a brand new monitor is allowed to have defective pixels, the number is published, and a single dead pixel is almost always inside it.
The standard
ISO 9241-307, which superseded the older ISO 13406-2, defines pixel fault classes. Defects are counted in three types:
- Type 1: a pixel permanently on (bright).
- Type 2: a pixel permanently off (dark).
- Type 3: a defective subpixel, where one of the three colour elements has failed.
Allowances are per million pixels.
| Class | Type 1 (bright) | Type 2 (dark) | Type 3 (subpixel) |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| I | 1 | 1 | up to 2 |
| II | 2 | 2 | up to 5 |
| III | 5 | 15 | up to 50 |
| IV | 50 | 150 | up to 150 |
Almost every consumer monitor, laptop and television is sold as Class II. Class 0 and Class I panels exist but are specialist and priced accordingly.
What Class II means for your screen
Because the allowance is per million pixels, a higher resolution panel is allowed more defects. This is the part that catches people out.
| Resolution | Pixels | Class II allows |
|---|---|---|
| 1920 × 1080 | 2.07 million | 4 bright, 4 dark, 10 subpixel |
| 2560 × 1440 | 3.69 million | 7 bright, 7 dark, 18 subpixel |
| 3840 × 2160 | 8.29 million | 16 bright, 16 dark, 41 subpixel |
So a 4K monitor with six dead pixels can be entirely within specification, and a warranty claim on it will be refused. That is not the manufacturer being difficult, it is the published standard being applied.
The better route: return, not warranty
This is the practical takeaway.
A retailer return inside the return window has no pixel threshold to argue about. You are returning an item you are entitled to return, and the reason barely matters. A warranty claim has to clear the class threshold, and on a high resolution panel that bar is high.
So test a new screen the day it arrives, not a month later. If you find anything:
- Photograph it with the colour that shows it most clearly, black for a bright pixel and white for a dark one.
- Note the date.
- Start the return immediately rather than deciding whether you can live with it.
You can always decide to keep it. You cannot always reopen a closed return window.
Before you count
Clean the screen. A large share of suspected dead pixels are dust or dried specks, and they look identical at a glance.
Then count in a dark room, working systematically across the panel rather than looking at it as a whole, and go through white, black and each primary colour. Record each defect as bright or dark, because the thresholds treat them differently and bright ones are counted more strictly.
What is not a pixel defect
Backlight bleed, the uneven brightness at the edges of a dark screen, is a characteristic of edge lit LCD panels rather than a pixel fault. It is only a warranty matter if it is severe.
Clouding and uniformity variation on grey are likewise normal on most panels, and faint vertical banding is common on cheaper IPS displays.
A partially failed pixel, where one subpixel is dead, counts as Type 3 rather than as a dead pixel, and the allowance is much larger. These look normal on most content and only show on one primary colour.
Common questions
Why does my manufacturer allow any dead pixels at all?
Panel yields. Manufacturing a display with zero defects across millions of pixels is achievable but expensive, and rejecting every panel with one flaw would raise prices substantially. The ISO classes exist to set a consistent, published line rather than leaving it to argument.
Is a bright pixel treated differently from a dark one?
Yes, and more strictly. A permanently lit pixel is far more noticeable than a dark one, especially on dark content, so Class II allows the same small number of each but Class III allows 5 bright against 15 dark. Some premium monitors advertise a separate zero bright pixel policy.
My monitor has one dead pixel and they refused the claim.
That is consistent with Class II, which permits up to 2 bright and 2 dark per million pixels. On a 1080p panel that is roughly 4 of each. A single defect is comfortably inside the allowance, which is why a retailer return inside the return window is usually the better route.
Does the position of the defect matter?
Sometimes. Some manufacturers apply a stricter standard to defects in the centre of the screen than at the edges, on the reasonable basis that a centre defect is far more intrusive. Check the specific policy rather than assuming.
What about laptops and phones?
The same classes are commonly referenced, but policies vary more and some manufacturers publish nothing at all. Retailer return windows matter even more in those cases, since there is often no published threshold to appeal to.