I always thought that green fits best if you want to indicate a successful connection. But I recently noticed that our router at work uses blue LEDs. Is there any difference in their meaning?

Like green indicates "everything works fine" and blue indicates "everything works fast"?

Edit: Some proof that may support the "blue = fast" theory:


All regions that currently have google fiber are blue (and fiber is the fastest available connection on earth)

  • 4
    This may not be a usability-backed decision. High-power blue LEDs seem to be a current fashion in electronics, possibly because they were invented much later than other colors, and a few years ago, they were hard to produce and expensive, the scarcity/expense rendering them attractive for case modders. Now they are cheap, they are built into practically everything. As I am sitting here, my PC case, keyboard and new monitor all use blue LEDs whereas the old monitor (7-8 years old) uses a green one.
    – Rumi P.
    Commented Sep 16, 2013 at 9:29
  • Blue is somewhat of a meaningless color, unlike red and green which have the meanings stop and go. White is also a relatively meaningless color, but blue is less distracting.
    – obelia
    Commented Sep 16, 2013 at 19:53
  • @RumiP. Your comment seems to be the best so far. +1 for that, and I would also accept it if it was a "real" answer.
    – Marc
    Commented Sep 17, 2013 at 18:16
  • @MarcMosby thank you. I took the time to expand this to an actual answer.
    – Rumi P.
    Commented Sep 18, 2013 at 12:17

4 Answers 4


I don't think that this decision was based on usability considerations.

In product design, there are as much trends as in clothing fashion. Computers and peripherals used to be beige boxes, but once they became "home electronics", they started getting trendy designs.

A guess at why blue LEDs became so popular: Earlier, it was impossible to create high-powered LEDs in blue. When a manufacturing process was discovered in the mid-1990s, the first ones on the market were rare and expensive, giving a sense of exclusivity to the early adopters (case modders) who used them. Then cheaper mass-production methods were discovered, and suddenly, everybody got to play with the cool blue lights. Which started a trend, and they started being used everywhere, not because the color provides some important information, but because a device using them looks like a trendy new model to the potential buyer.

As an example, the equipment on my desk is about a year old, except for my second monitor. Keyboard, PC case and the first monitor are all black with blue LEDs. The second monitor is from the late 2000s, with a case in a black-and silver combination, and uses green LEDs. I have observed these exact color combinations in many other electronic devices, e.g. car radios and induction stoves.

As for the actual usability of the blue LEDs, I find it lower than that of other colors. First, they tend to emit more light. It is actually distracting, when one tries to darken a room with running electronics. Second, I have a slight non-correctable visual defect of seeing "dandelions" of rays around small light sources. It is much worse in the blue portion of the spectrum, and pure blue light, such as from blue LEDs, is the worst offender. If there are two blue LEDs close to each other, I am not able to tell which one is on and which one is off unless I am very close to the device, which certainly reduces the usability of devices with rows of blinkenlights.


If there is just one status (or if each status has an appropriate label next to it) then the colour choice is irrelevant as long as the on and off status are easily distinguishable. When there are a number of different status you need to represent, green and red are not ideal colours due to colour accessible design. It would be pointless having an indicator for 'everything works fast' unless you can show the relative degree (e.g. number of bars). I am not aware of blue having any other meaning when used as a status indicator.


I'm not sure there's a hard, fast color choice for a status indicator. Like most "rules", they are guidelines. Yet the biggest thing to keep in mind is the context of your product is what matters most. Are you already using blue a lot? For links? Background colors? Is it a core color to your color palette? If so, then you might want to consider using a different color like green. If blue isn't a core color and if it wouldn't confuse the user within the context of your product, then I think you are fine.

Within OSX Mountain Lion, Apple has used the green-red color circles to denote connection status and blue circles to indicate user-interaction status.

Mail (for Mac, OSX Mountain Lion) uses a blue indicator bubble next to the message to indicate a new or unread status.

Mail (for Mac, OSX Mountain Lion) uses a blue indicator bubble next to the message to indicate a new or unread status.

The Messages App for Desktop Mac uses green, yellow and red bubbles to indicate available, idle and away statuses.

The Messages App for Desktop Mac uses green, yellow and red bubbles to indicate available, idle and away statuses. This example is probably closest to the one you have cited. One thing to note with Messages is that it also uses the blue circle metaphor as well to help users note which messages are read and unread.

I would advise you to look at the context of your app. Does it make sense to use green, yellow, orange or red status indicators within the context of your app? Are there other symbol and color patterns you're already establishing elsewhere that can be reinforced here? Maybe blue makes sense. Maybe green is better. Or maybe a filled white circle (connected) contrasted with an outlined, empty white circle (not connected) can indicate the same message. Again, the context of your product is what matters most.


In my opinion, the color blue is chosen because it look cool to many. It's already integrated as part of the product design. And of course, the color red always refer to error or mistake.

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