A hospital loses 30 wheelchairs a month. Not stolen — just missing. A factory cannot find 12 percent of its torque tools on any given Friday. Asset tracking promises to fix this, but the first question is rarely asked: which tracker do you actually need? For most teams the choice comes down to a BLE Tag and an UWB tag, and the two are easy to confuse because both hang off a pallet and both report location.
Two radios, two physics
A BLE Tag estimates distance from received signal strength. The farther you are, the weaker the signal, and a simple model turns that weakness into meters. An UWB tag does something harder: it measures the flight time of a nanosecond-scale pulse, so it reads distance directly. That single difference drives everything else — accuracy, battery life, and cost.
Accuracy in the real room
On paper BLE gives you 1 to 3 meters with RSSI, tightening to roughly half a meter if you add angle-of-arrival antennas. UWB lands at 10 to 30 centimeters. But paper lies. Walls, metal racks, and human bodies bounce the signal, and in a busy warehouse the BLE number can swing by two meters between readings. UWB resists this because its pulse is too short to be fooled by a single reflection. If you need to know which shelf a tool sits on, only UWB tells you.
Battery is the quiet constraint
A BLE Tag on a CR2032 coin cell runs one to three years because the radio sleeps 99 percent of the time and only blinks during an advertisement. An UWB tag measures constantly and burns tens of milliamps doing it, so the same coin cell dies in months. You can bolt on a bigger battery, but that changes the tag from a sticker into a brick. For 5,000 low-value totes, BLE wins on battery alone.
What the infrastructure costs
People price the tag and forget the rest. A BLE Tag leans on gateways you may already have — one every 500 to 1,000 square meters covers a floor. UWB needs anchor points, ideally four per zone, mounted with clear line of sight and carefully surveyed positions. The anchors cost more than the tags they serve, and commissioning them is a project, not a plug-in.
When BLE is enough
Pick a BLE Tag when the asset is cheap, the count is high, and “near the west dock” is good enough. Returnable transport items, library books, and shared hospital wheelchairs fit this perfectly. A monthly audit that finds the missing 5 percent is a win, and you do not need centimeter precision to walk a cart to the right aisle.
When UWB earns its price
Choose UWB when a mistake is expensive. Autonomous guided vehicles must not collide, so they need to know a peer is 40 centimeters away, now. Tool tracking inside a live surgery suite, where a retained instrument is a catastrophe, also justifies the cost. If the asset itself is worth more than the whole tracking system, pay for precision.
A hybrid that ships
You do not have to pick one. A BLE Tag on every item gives cheap, building-wide presence. Drop UWB anchors only into the two zones where precision matters — the receiving bay, the sterile core. The system tags 10,000 items with BLE and resolves conflicts to 20 centimeters only where it counts. This is what most mature deployments look like two years in.
A short comparison
| Factor | BLE Tag | UWB tag |
|---|---|---|
| Typical accuracy | 1-3 m (0.5 m with AoA) | 10-30 cm |
| Battery life | 1-3 years | months |
| Infrastructure | gateways, 1 / 500-1000 m2 | anchors, ~4 / zone |
| Tag cost | $1-3 | $5-15 |
| Best for | high-count, low-value | high-value, precise |
One field story
A regional hospital put a BLE Tag on every wheelchair and cut “lost” calls by 80 percent in the first quarter. They had tried UWB first, on a pilot of fifty chairs, and abandoned it: the anchors cost more than the chairs they tracked, and the batteries died before the trial ended. The lesson was not that UWB is bad. It was that the chair only needed to be findable, not located to the inch.
The trade you accept
There is no free tracker. BLE trades accuracy for years of battery and a fifth of the cost. UWB trades battery and budget for certainty you can act on. Name the failure mode you are actually preventing, then buy the radio that stops it — not the one with the better brochure.
