What Is Ultra-Wideband (UWB)? How It Works on Your Phone

Ultra-Wideband, or UWB, is a short-range radio technology that is separate from Bluetooth and Wi-Fi and is built for one specific job: measuring the precise distance and direction between two devices, down to roughly centimeter-level accuracy, rather than estimating "near" or "far" from signal strength. On phones, that is what lets an iPhone draw an arrow pointing straight at a lost AirTag, lets a Galaxy phone show exactly which drawer a SmartTag2 is hiding in, and lets some cars unlock the moment your phone, still in your pocket, gets close to the door handle.

How Ultra-Wideband Actually Works

Most short-range wireless tech on your phone — Bluetooth Low Energy (BLE), Wi-Fi, NFC — sends data by modulating a narrowband radio carrier. Ultra-Wideband does something different. As Wikipedia's technical summary of the standard explains, UWB spreads its signal across a very wide slice of spectrum and sends it as a series of extremely short pulses rather than by varying a continuous carrier wave's amplitude, frequency, or phase. Under the U.S. Federal Communications Commission's 2002 rules, unlicensed UWB devices can use roughly 3.1 to 10.6 GHz of spectrum at very low power, and a signal only counts as "ultra-wideband" if its bandwidth exceeds the lesser of 500 MHz or 20% of its center frequency.

That wide bandwidth and pulse-based signaling matter for one reason: timing. Because a UWB pulse is so short, a receiver can measure its time of arrival with much finer resolution than it could measure the strength of a Bluetooth or Wi-Fi signal. Two UWB radios can run a "two-way ranging" exchange — essentially timing how long a pulse takes to bounce from one device to the other and back — and from that timing alone calculate distance with centimeter-level precision. Add a second or third antenna on one side, and the system can also calculate the angle the signal arrived from, which is what lets a phone show not just "how far" but "which direction."

Bluetooth can estimate rough proximity using received signal strength (RSSI), and newer Bluetooth direction-finding features add some angle estimation, but neither approach gets close to UWB's ranging accuracy, which is why Apple, Samsung, and the broader industry standards body behind UWB, the FiRa Consortium, all describe fine-grained "ranging" as the technology's core strength.

UWB vs. Bluetooth LE vs. NFC: What's the Difference

These three radios often sit inside the same phone, and they get confused because they're all used for "nearby" interactions — but they solve different problems, and understanding the difference is the key to understanding what UWB is actually for.

• NFC (Near Field Communication) works at a range of a few centimeters and is built for a quick tap-based handshake — think contactless payments or unlocking a hotel room door. It doesn't do continuous distance tracking; it's essentially a touch-based exchange. (For how that works day to day, see our explainer on how NFC-based tap to pay works on iPhone and Android.)
• Bluetooth Low Energy is built for low-power data exchange over tens of meters and is what powers AirTag's crowdsourced Find My network, SmartThings Find's basic tracking, and most wireless accessories. It can estimate rough proximity from signal strength, but that estimate is noisy and easily thrown off by walls, bodies, or interference.
• Ultra-Wideband is built specifically for precise ranging and direction over roughly tens of meters, using time-of-flight pulses instead of signal-strength guesses. It is the only one of the three designed to reliably answer "exactly how far, and exactly which way."

In practice, these radios are often used together rather than as substitutes for one another. A digital car key, for example, typically authenticates over Bluetooth Low Energy first and only then opens a UWB ranging session to pinpoint exactly how close the phone is to the door — with NFC kept as a fallback if the battery is dead.

Which Phones Have UWB

UWB has quietly become common in flagship and upper-midrange phones since 2019, though it's still not universal. Here's a snapshot of where it shows up, based on each company's own documentation.

The practical takeaway: if a phone has UWB, its settings app will usually mention "Ultra Wideband" explicitly (often with a toggle to turn it off), and the feature only works between two UWB-equipped devices — it cannot "reach" into a phone or tag that lacks the radio.

Apple's U1 Chip and Nearby Interaction

Apple was the company that took UWB mainstream, building its U1 chip into the iPhone 11 in 2019. Apple's own Platform Security documentation describes the U1 chip as giving iPhone "spatial awareness" so it can precisely locate other U1-equipped Apple devices — the feature that, paired with AirTag, became known as Precision Finding: an on-screen distance readout, an arrow, and haptic buzzes that get more intense as you close in on a lost item.

Apple also opened this up to developers through its Nearby Interaction framework, introduced for iOS 14 and expanded at WWDC. Nearby Interaction lets third-party apps measure distance and direction to another Nearby Interaction–compatible device or accessory; Apple's developer documentation describes an additional ARKit-assisted mode (enabled by setting isCameraAssistanceEnabled on a session's configuration) that widens the usable field of view by combining the UWB ranging data with the phone's camera-based spatial tracking — the same underlying approach used for AirTag's Precision Finding experience.

Apple's current support documentation lists Precision Finding as supported on iPhone 15 and later models plus iPhone Air — reflecting Apple's newest-generation UWB hardware and the devices still covered by its latest iOS releases, separate from the original U1-based ranging that launched on iPhone 11.

Samsung's UWB and the Galaxy SmartTag2

Samsung's clearest consumer use of UWB is the Galaxy SmartTag2, announced through Samsung Newsroom in 2023. Unlike the original SmartTag line, which split Bluetooth-only and UWB versions into separate SKUs, the SmartTag2 combines both radios in a single tracker. Samsung's own release describes an improved "Compass View" in the SmartThings Find app that shows live direction-and-distance arrows to a nearby tag — a feature that, per Samsung, requires pairing the tag with a UWB-enabled Galaxy phone, such as the Galaxy S23 Ultra, rather than just any Android device.

That UWB-powered Compass View sits alongside SmartThings Find's broader Bluetooth- and network-based tracking (similar in spirit to Find My), and it's the direct Samsung equivalent of Apple's Precision Finding: short-range, high-accuracy guidance for the final few meters of a search, layered on top of longer-range Bluetooth and crowdsourced location.

UWB on Android and Google's APIs

At the platform level, Google built UWB support directly into Android starting with Android 13, according to the Android Open Source Project's own documentation. The architecture has two layers: a default platform module (com.google.android.uwb) that handles the ranging logic, paired with a hardware abstraction layer that each chipset vendor supplies for their specific UWB radio. That HAL interface deliberately follows the UWB Command Interface (UCI) specification published by the FiRa Consortium, so Android's framework and the underlying silicon speak a common protocol regardless of chip vendor.

For developers, AOSP's documentation is explicit that direct, low-level access isn't the supported path for ordinary apps: third-party apps are meant to use the Jetpack androidx.core.uwb public API, which exposes ranging sessions and capability checks without touching the system-level UWB manager that's reserved for privileged system apps. This is a separate API surface from Nearby Connections, Google's peer-to-peer data-transfer API, though the two can be used together in an app that needs both "how close is this device" (UWB ranging) and "send this device a file" (Nearby Connections). As Android's feature set keeps expanding with releases like Android 17 — covered in our rundown of what's new and which phones support it — UWB ranging is one of several lower-level radio capabilities app developers can increasingly rely on being present across more devices.

Digital Car Keys and UWB

One of UWB's biggest real-world jobs doesn't happen in a Find My app at all — it happens at your car door. The Car Connectivity Consortium (CCC), the cross-industry standards body behind the "Digital Key" specification used by Apple, Samsung, and a long list of automakers, built UWB into its Digital Key Release 3 specification specifically to add hands-free, location-aware access. According to the CCC's own published materials, Release 3 authenticates the phone or smartwatch over Bluetooth Low Energy and then uses UWB's precise ranging to confirm exactly how close the device is to the vehicle — the mechanism that lets a car unlock as you approach with your phone still in your pocket, rather than requiring you to tap it against a reader. NFC remains a mandatory fallback in the spec for cases like a dead phone battery.

This is a good example of how UWB tends to work in practice: it's rarely the only radio in the room. It is the ranging layer added on top of Bluetooth's broader-range discovery and NFC's tap-based backup, contributing the one thing neither of those does well — reliable, precise distance.

The FiRa Consortium and UWB Standards

UWB's ability to work the same way across an iPhone, a Galaxy phone, and a car from a totally different manufacturer isn't an accident — it's the job of the FiRa Consortium, the nonprofit industry group dedicated to UWB interoperability. According to FiRa's own materials, the group was formed in 2019 by companies including Samsung, NXP, and Bosch to make sure UWB devices from different vendors could reliably work together as the technology spread, and its name itself is shorthand for "fine ranging," a nod to the accuracy that sets UWB apart. FiRa's technical work builds on the IEEE 802.15.4z standard and defines the certification programs — including the UCI interface Android's own UWB stack follows — that let a UWB chip from one manufacturer talk to a UWB chip from another.

FiRa has also extended its certification work to cover specific applications beyond simple device-finding, including the UWB portion of the CCC's Digital Key and newer UWB-based access-control schemes for doors and buildings — effectively acting as the plumbing standard that specialized applications like Find My, SmartThings Find, and car keys all sit on top of.

Battery Life and Privacy Considerations

UWB radios are designed to be used in short bursts rather than running continuously, which is why phone makers generally only fire up ranging when an app actively needs it — say, while the Find My app is actively guiding you to an AirTag, or while your phone is approaching a UWB-equipped car door — rather than leaving it scanning at all times. That's a similar power philosophy to other proximity and short-range radios on your phone, including wireless charging standards like Qi2, which also limit active radio or power use to the moments a nearby compatible device is detected.

On privacy, Apple's own security documentation notes that the UWB technology underpinning the U1 chip also supports broader privacy protections elsewhere on the device, such as randomizing a phone's MAC address and Wi-Fi frame sequence numbers, rather than the ranging feature itself constantly broadcasting a fixed identifier. Because precise ranging data is sensitive by nature — it can reveal exactly how far away, and in what direction, a specific device is — both Apple's and Samsung's implementations tie UWB ranging sessions to an authenticated pairing between known devices (an AirTag already registered to your Apple ID, a SmartTag2 already linked to your Samsung account, or a phone already enrolled as a car's digital key) rather than allowing any nearby UWB radio to range against your phone. Regulatory rules also shape where UWB can run at all: because UWB shares spectrum with other licensed uses, some countries restrict or disable it, which is why a feature like Precision Finding can simply stop working if you're traveling in a region where UWB transmission isn't authorized.

What's Next for UWB

UWB's trajectory so far has been a steady expansion from a single Apple accessory feature into a shared, cross-industry ranging layer: more phone makers building it in, the FiRa Consortium certifying an increasing number of specific use cases (device finding, car keys, and now building access control), and Android formalizing platform-level support so third-party developers don't need to work around vendor-specific hardware. The clearest next steps to watch are broader digital-car-key rollouts as more automakers adopt the CCC's UWB-equipped Digital Key release, continued growth in UWB-based building and access-control certifications from FiRa, and — as both Apple's and Google's device-finding tools keep evolving — closer integration between UWB ranging and the broader "find my stuff" apps and networks that already rely on Bluetooth and crowdsourced location, rather than UWB being treated as a separate, standalone feature.

Written byNadia Osei

Nadia Osei covers mobile and consumer gadgets for Pandromeda: smartphones, tablets, smartwatches, earbuds and smart-home devices. She tracks launches, software updates and pricing across Apple, Google, Samsung and the rest, and builds comparisons from the manufacturers' published specifications.

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