Bluetooth class 1 vs class 2: what long range really means

Bluetooth class 1 vs class 2 is a question about transmit power and nothing else: class 1 radios may transmit at up to 100 milliwatts, class 2 radios at up to 2.5 milliwatts. Every other difference people attribute to the classes — better audio, faster pairing, cleverer tracking — is imaginary. If you are reading listings that advertise a "class 1 long range Bluetooth tracker", this piece explains what that claim can and cannot mean.

What is a Bluetooth power class?

A cap on how much radio power a device is permitted to put into its antenna, set by the specification for interference and safety reasons.

Bluetooth Classic — the flavour used by headsets, speakers and car audio — defines three.

Class 2 is the ordinary case: the overwhelming majority of consumer Bluetooth devices are class 2, because more power means shorter battery life and most products do not need the distance.

Does Bluetooth Low Energy use the same classes?

No, and this is where most listings go wrong.

Low Energy defines its own power classes, and they do not map onto the classic ones. LE devices are grouped by maximum output as well, with a top class permitting 20 dBm, an intermediate class at 10 dBm and lower classes at 4 dBm and 0 dBm. A finding tag is a Low Energy device and is nowhere near the top of that scale, because a tag that transmitted at 100 mW would flatten its coin cell in weeks rather than running for years.

So a product described as a "class 1 tracker" is at best using the classic vocabulary loosely and at worst using it decoratively. The number that would actually tell you something — the transmit power in dBm — is almost never published.

Which matters more: power or the receiving end?

The receiver, and by a wide margin.

Range is set by a link budget: transmit power, minus everything lost along the way, against the sensitivity of the receiving radio. Raising transmit power is only one of three terms, and it is the expensive one.

Because free-space loss costs roughly 6 dB every time distance doubles, the arithmetic is unforgiving. Going from 4 dBm to 10 dBm is a 6 dB gain, which buys you a doubling of range in ideal conditions — and rather less in a house, where obstacles dominate. Quadrupling the power for another 6 dB drains the battery four times as fast to double it again.

This is why the honest way to extend a tag's usable reach was never more power. It was to change what happens past the edge of the radio link, which is what a crowd-sourced network does.

What does "long range" mean on a tracker listing?

Usually either a class 1 claim the device does not honour, or the Bluetooth 5 long-range coded mode, which tags do not use for finding.

Bluetooth 5 introduced LE Coded PHY, a mode that trades data rate for robustness by adding forward error correction, and the specification's headline claim was up to four times the range of the standard LE mode. It is real, it is useful in industrial telemetry, and it is largely absent from consumer finding tags — it costs airtime and power, and it requires support at both ends, including in the phone.

Treat any tracker listing that quotes a three-figure range in metres as quoting a line-of-sight laboratory figure. Our guide to what walls and metal do covers what survives of such a figure in a real building, and our ten-minute range test lets you measure yours rather than trust anybody's.

Which class should a buyer actually look for?

None of them. Look at what happens when the tag is out of range instead.

For a finding tag, the radio class is close to irrelevant to the outcome you care about. Whether you find your keys in the house is decided by the speaker. Whether you find a bag left in a café across town is decided entirely by how many devices are listening for the tag on its owner's behalf.

A class 1 tag with no network behind it will tell you nothing the moment it is out of sight. A modest class 2 tag on a large network will keep reporting from another city. That is the comparison worth making, and it has nothing to do with milliwatts.

How BlueTag is specified

BlueTag is an ordinary low-power Bluetooth Low Energy device, and we quote its link as up to 60 m / 200 ft in the open because that is the figure the hardware achieves with clear air in between. We do not describe it as class 1, because it is not, and a tag that was would not run for up to two years on a single CR2032.

What closes the gap is the pair of things either side of the radio. Inside the link, an 80–100 dB buzzer your iPhone can trigger, which locates an object by ear far more reliably than any signal-strength reading. Outside it, the Apple Find My network: passing Apple devices hear the broadcast and report an encrypted position only your Apple Account can decrypt, with no SIM in the tag and no data cost to you.

The honest limits, stated once: iPhone and iPad only, from iOS 14.5, with no Android support whatsoever, and no Ultra Wideband so no on-screen arrow. IP67 sealed, 36.3 × 36.3 × 9 mm, about 10 g, two tags and two key rings in a box for under £15 with free UK delivery and 30 days to send it back. See the full specification.