Working in IT, I pair Bluetooth devices without a second thought: headsets, keyboards, mice, phones, the speaker in every meeting room. It took me an embarrassingly long time to ask the obvious question: why is Bluetooth called Bluetooth? It is not an acronym, it says nothing about how the technology works, and nothing about it is blue.
The answer is a story in two halves, separated by a thousand years. One half belongs to a Danish king with a nickname nobody can fully explain. The other belongs to a handful of engineers in the 1990s who needed a code name for a project and never got around to replacing it.
A king, a runestone and a kingdom
The name comes from Harald Gormsson, known in Danish as Harald Blåtand and in English as Harald Bluetooth. He ruled Denmark from around 958 to 986, according to The Collector, in the closing decades of the Viking Age.
What we know about him comes largely from the Jelling stones, two great runestones in Jutland. The larger was raised by Harald in memory of his parents, and its inscription, as Wikipedia notes, credits him with uniting Denmark and converting the Danes to Christianity. He also held territory in Norway during his reign. Danes often call the stone the country’s birth certificate, and it is the same stone that would eventually turn up, in a photograph, in front of an engineer at Intel.
The tooth nobody can prove
Ask most people where the nickname came from and they will tell you Harald had a rotten tooth that had turned dark. It is a good story, and it may even be true, but it rests on surprisingly little. The nickname only appears in writing around two centuries after Harald’s death, and as National Geographic puts it, there is no hard evidence about the state of his teeth.
The language does leave the door open. The Old Norse word for blue could also mean dark or blue-black, so a “blue tooth” might well have been a black one. But some historians doubt the name had anything to do with teeth at all. The honest position is that the rotten tooth is a tradition rather than a fact, which turns out to be a fitting start for a name that was never meant to last.
Enter the engineers
By the mid-1990s, phones, laptops and other devices needed a simple way to talk to each other without cables, and every company was heading in its own direction. Anyone who has worked in IT will recognise the problem: plenty of solutions, none of them compatible. In 1996, Intel, Ericsson and Nokia met to plan a single standard for short-range radio, and during that work, the Bluetooth Special Interest Group says, Intel’s Jim Kardach suggested Bluetooth as a temporary code name.
Kardach’s own account of naming Bluetooth explains where it came from. He had been talking Viking history with an engineer from Ericsson, who told him about The Long Ships, a Swedish novel in which Harald Bluetooth appears as king. Kardach went digging and, as Wikipedia recounts, found a picture of Harald’s runestone in a history of the Vikings. The parallel was obvious. Harald was, in Kardach’s words, “famous for uniting Scandinavia”, and this project was meant to unite the PC and mobile phone industries with one wireless link.
The name that won by default
Nobody intended Bluetooth to be the real name. When the time came to choose one, the shortlist was RadioWire and PAN, short for Personal Area Networking, and Kardach writes that PAN won the vote. Then it ran into a very modern problem. A search turned up tens of thousands of existing uses of “PAN”, so it would have been almost impossible to stand out online or to protect as a trademark, and the trademark search on RadioWire could not be finished before launch. With the deadline looming, the industry group went public in 1998 under the only name left standing. By the time anyone could have revisited it, the press had been writing about “Bluetooth” for months.
| Year | What happened |
|---|---|
| c. 958 to 986 | Harald Gormsson rules Denmark and raises the great Jelling stone |
| 12th century | His nickname, Bluetooth, first appears in writing |
| 1996 | Intel, Ericsson and Nokia meet to plan a common short-range radio standard |
| 1997 | Jim Kardach proposes “Bluetooth” as a temporary code name (accounts differ on whether this was late 1996 or 1997) |
| 1998 | The Bluetooth SIG launches with Ericsson, IBM, Intel, Nokia and Toshiba, still using the code name |
A king’s initials on your phone
The logo carries the same story. As the Bluetooth SIG explains, it is a bind rune: two runes from the Younger Futhark, the alphabet of Harald’s time, merged into one symbol. Hagall (ᚼ) stands for H and Bjarkan (ᛒ) for B, so the icon in your phone’s settings is Harald Bluetooth’s monogram. It is a surprisingly direct line from a 10th-century runestone to the menu you tap every time you connect your earbuds.
What I like most about this story is how unplanned it all was. A king’s nickname that may not even mean what we think, picked up from a novel during a chat between engineers, chosen as a stopgap and kept only because the better options fell through, now sits on billions of devices. If you are curious about the radio waves that make it work, my post on whether 5G is safe covers the science, and the history of the internet tells the story of how we got connected in the first place.
Where this story comes from: the naming details are from Jim Kardach’s own write-up and the Bluetooth SIG’s official history, the dates of Harald’s reign from The Collector, and the debate over his nickname from National Geographic and Wikipedia’s article on Harald Bluetooth, all linked above.