“Which one should we use?” The honest answer is “it depends,” which is useless when you’re the one signing the purchase order. So we stopped answering and started measuring: same floor, same year, both radios.
What each radio actually does
Passive UHF RFID works like a mirror. The reader shouts energy, the tag reflects a bit of it back with its ID. There is no battery in the tag at all. A BLE Tag is the opposite: it carries a coin cell, broadcasts its ID on a schedule, and a gateway somewhere nearby listens. That single difference — borrowed energy versus carried energy — is what every other trade-off grows out of.
The read-rate number nobody advertises
UHF vendors quote a thousand reads per second. That number is real, and it’s measured on cardboard, in a clear beam, in a demo. Put the tag on a steel tool case or a pallet of canned soup and the read rate falls off a cliff, because metal detunes the antenna and water absorbs the energy. A BLE Tag at 2.4 GHz doesn’t detune the same way, but water still eats it, and a pallet of beverages is hard on both radios. Ask for the read rate on your material, not theirs.
Chokepoint truth versus ambient presence
This is the real fork, and it matters more than range. RFID tells you “this pallet crossed THIS door at 14:32.” That’s chokepoint truth — the kind of sentence an auditor accepts. A BLE Tag tells you “the pallet is somewhere in zone C.” Weaker per reading, but you learn where things sit, not just where they passed. If your process has doors, RFID’s certainty is hard to beat. If your process has aisles, presence beats precision.
What the tags cost versus what the readers cost
Passive RFID tags run ten to fifty cents. The readers run five hundred to two thousand each, and you need one per doorway. A BLE Tag costs one to five dollars, and a gateway is fifty to two hundred covering a few hundred square meters. So the arithmetic flips with the shape of the job: ten thousand totes spread over a wide floor, BLE wins on infrastructure. Two hundred tools moving through three doors, RFID wins outright.
The battery you’re signing up for
A passive RFID tag has no battery and will outlive the pallet it’s stuck to. A BLE Tag is a battery, and at ten thousand units that’s a maintenance program, not a purchase. You’ll schedule swaps, you’ll chase the ones that die early in the cold room, and you’ll budget for it every year. This is the single most legitimate reason teams pick RFID, and it deserves to be said plainly instead of buried in a spec sheet.
What our year of data actually said
We tagged eight thousand totes with a BLE Tag and four hundred tool kits with RFID. The totes needed “which aisle is it in” — BLE answered that. The tools needed “did it leave the cage” — RFID answered that, at the door, with a timestamp nobody could argue with. Both worked. Neither replaced the other, and after about a month the floor staff stopped caring which radio had won our argument.
If someone made me pick one
Ask what question you’re actually answering. “Where is it, roughly, right now?” is a BLE Tag question. “Did it cross this line?” is an RFID question. If you need both, run both, and don’t let a vendor tell you their radio answers everything — it doesn’t, and the year of data is the proof.
We still run both. The warehouse never once asked us to choose.
