RTLS accuracy: what the numbers actually mean.
Every RTLS supplier quotes an accuracy number. They mean different things. UWB is usually the most precise of these options. The accuracy you get depends on your site, and we confirm it in the survey.
Per-technology realistic accuracy under production load.
UWB is usually the most precise of these options. The accuracy you get depends on your site, and we confirm it in the survey.
The accuracy depends on your site, and we confirm it in the survey.
RAIN RFID (location-grade): 1-3 m at item-level under a ceiling phased-array; presence at portal read points.
GPS / GNSS (standard): 3-5 m outdoor; does not work indoors.
The accuracy depends on your site, and we confirm it in the survey.
LoRaWAN geolocation: 100-500 m via TDoA across multiple gateways; good for presence, not position-precise.
The accuracy depends on your site, and we confirm it in the survey.
Why supplier accuracy claims are usually 95th percentile under lab conditions.
Most spec-sheet numbers assume line-of-sight, designed-density placement, calibrated mounting, no production-load interference, single-tag testing.
Real production environments degrade those numbers, sometimes badly.
Ask suppliers to quote 95th-percentile accuracy under your environment. They will resist; that resistance is the answer.
How accuracy degrades: the five common causes.
Multipath from metal racking, glass, stainless panels, concrete-aggregate floors, HVAC ducting.
Anchor mounting height drift: 200 mm off design changes the UWB cone of coverage noticeably.
Synchronisation drift: TDoA requires nanosecond sync; mis-cabled PoE switch quietly destroys accuracy.
RF blockers introduced post-survey: racking, guarding, mezzanines.
Production-load interference: forklift mast occlusion, dock-door cycles, press cycles.
Comparing options? Try the free technology selector →
Specifying accuracy so suppliers cannot hide behind lab numbers
RTLS accuracy is meaningless without percentile, environment and use-case conditions. The accuracy depends on your site, and we confirm it in the survey. Operators should specify accuracy as: technology + percentile (50th and 95th) + environment class (open / partitioned / metal-heavy) + tag motion + update rate + whether first-path NLOS was present. That sentence is what belongs in RFPs and pilot gates.
Realistic production bands. UWB is usually the most precise of these options. The accuracy you get depends on your site, and we confirm it in the survey. BLE AoA: roughly 0.5-3 m depending on density and multipath; BLE RSSI alone is typically multi-metre zone-level. Wi-Fi RTT: often 1-5 m depending on AP density. Passive RFID portals: not continuous accuracy. They deliver presence at a read point with a read-rate KPI instead.
Match accuracy to the locating decision. Warehouse asset find: 1-3 m may be enough. Ward equipment: room-level. WIP station presence or OR table distinction: sub-metre. The accuracy depends on your site, and we confirm it in the survey. Paying for UWB everywhere to answer room-level questions is a common budget failure.
Why pilots look better than day 60. Empty bays, ideal tag mounts, low traffic and supplier-tuned filters inflate early numbers. Production load adds mast occlusion, moving metal, body shadowing and layout drift. Build acceptance tests for peak conditions and re-measure after the first layout change.
Contracting tip. SLAs that only guarantee accuracy under the installer’s commissioning conditions are weak. Tie acceptance to your operational KPI and percentile under agreed live-load scenarios, and keep a remediation path (retune density/orientation) before any automatic hardware uplift.
Reporting accuracy to boards and suppliers without losing the plot
Report locating accuracy as distributions over time and zone classes. A single site-wide average hides the cell that fails safety thresholds and the ward that already meets room-level needs. Pair accuracy charts with operational KPIs so leadership sees whether centimetres (or metres) actually changed search time, dwell or utilisation.
When suppliers present new firmware claims, re-run the same production-load script before accepting a contractual accuracy uplift. Firmware can help; it does not repeal multipath. Keep a living accuracy register per zone as part of ongoing operations, especially after layout changes.
For hybrid estates, never average UWB and BLE error into one number. Publish separate bands per radio layer so buyers and operators set expectations correctly.
Accuracy and latency are twin locating requirements
A precise fix that arrives too late cannot drive a safety interlock or a station confirmation. Specify latency alongside accuracy in every pilot gate. Some workflows tolerate multi-second BLE updates. Others need sub-second UWB. Measuring only centimetres while ignoring time-to-event produces systems that look accurate in reports and fail in operations.
Frequently asked questions
What accuracy does my use case actually need?
Asset tracking in a warehouse: 1-3 m. The accuracy depends on your site, and we confirm it in the survey. Hospital workflow: room-level (1-3 m), sub-metre for bed/equipment.
Why does my pilot accuracy drop on day 60?
Almost always because the bay was empty during commissioning and full of racking and traffic by day 60. The RF environment changed.
Can RTLS accuracy be guaranteed contractually?
Supplier SLAs guarantee accuracy under their installer’s commissioning conditions, not under your production load. That is why most programmes hit the SLA on paper and miss the operational KPI.
What is the difference between 50th and 95th percentile accuracy?
50th percentile means half of measurements are within that number. 95th percentile means 95% are. The accuracy depends on your site, and we confirm it in the survey.
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