Apple Watch Radiation: What It Actually Emits, and How to Check

If you are searching this, you have probably already found the shielding cases, the stickers and the pendants. What you have not found is anyone willing to say what an Apple Watch actually transmits.

So here is what is inside one, where the numbers come from, how to verify them yourself, and — since we make a competing watch and are not going to pretend otherwise — what a device built to transmit as little as possible looks like beside it.

The short answer

An Apple Watch emits radio-frequency energy — the non-ionising kind. It is the same category of emission as your router, your car key and your wireless earbuds, and it is a different thing entirely from the ionising radiation of X-rays or radioactive material, which carries enough energy per photon to break chemical bonds.

How much it emits depends on which radios are running. And an Apple Watch has more of them than almost anything else you wear.

What is actually inside an Apple Watch

From Apple’s own published specifications for the Series 10, the cellular model contains:

That is five radio technologies on one wrist. None of them is unusual for a phone, and that is rather the point — a cellular Apple Watch is a phone you wear, and it transmits like one because it has to.

The heaviest of them is LTE. Ordinary consumer cellular devices sit in a power class specified to transmit at up to 23 dBm — 200 milliwatts. That is a ceiling rather than a constant: cellular radios use adaptive power control and drop well below it when signal is strong, climbing toward it in a basement or a rural notspot.

How that compares with a watch built to stay quiet

The Tribe Watch was built around a different decision: your heart rate, sleep and activity are interpreted on your own device rather than uploaded to us for analysis. Once you make that choice, the watch has almost nothing to transmit — so it does not need Wi-Fi, and it certainly does not need a cellular modem.

Be careful with that last comparison, because we want you to trust the rest of the page. Our 0.91 mW is measured. The 200 mW is a class ceiling, not a figure from Apple’s own test report, and it describes a cellular radio rather than a Bluetooth one. The two numbers are not the same kind of number.

That is the difference worth understanding. Airplane mode is a setting — it can be turned back on, changed by an update, or simply forgotten on a night you meant to use it. A watch with no cellular radio in it cannot transmit on cellular under any setting, on any firmware, ever. The same applies to Wi-Fi.

What about SAR?

SAR — specific absorption rate — measures how much RF energy your tissue absorbs, in watts per kilogram. It is a different test from transmit power and it is the figure most often quoted in phone-radiation coverage.

Apple publishes RF exposure information for each Apple Watch model on its regulatory site, and if SAR is what you care about that is where to read it rather than anywhere secondhand.

How to check an Apple Watch yourself

Five minutes, free, and far more reliable than any article — including this one.

1. 1Get the FCC ID from the watch: Settings › General › Regulatory. Apple’s grantee code is `BCG`.
2. 2Search it at the FCC Equipment Authorization database, `fcc.gov/oet/ea/fccid`. First three or five characters go in Grantee Code, the rest in Product Code.
3. 3Open the grant, and read the Equipment Specifications table. Each line is one radio, with its frequency range and output power in watts.
4. 4Count the lines. That number tells you more than any single wattage does.
5. 5For SAR, go to Apple’s own regulatory pages rather than the FCC grant.

Do the same to us. Our ID is 2ASAU-S90 and it is the reason we can write this page at all — the full breakdown of what we found, including a Fitbit measured at 10.3 mW, is here.

So is it harmful?

We are not going to tell you it is, because that is not established, and a company selling you an alternative is the last source you should accept it from.

International exposure guidelines are built around tissue heating, and consumer wearables operate far below the levels at which measurable heating occurs. Harm below those limits has not been demonstrated. Anyone telling you otherwise while selling a shielding sticker is asking you to buy their conclusion along with their product.

What we will say is that wanting less of something does not require proof of harm. People choose lower-alcohol drinks and quieter appliances without producing a study first. A watch sits against your skin all day and all night, which a phone in your bag does not, and preferring one small radio there to five is a perfectly reasonable thing to want. You are entitled to the numbers that let you choose — which is the part this industry withholds.

What are you actually paying for?

Ask yourself how often you leave the house without your phone. For most people the honest answer is almost never — which means the cellular radio, the single heaviest transmitter on your wrist, is running for a capability you rarely use.

And it is not free. A cellular Apple Watch costs several hundred dollars, then a monthly line on your carrier plan for the rest of the time you own it. You are paying twice — once for the hardware, then every month — to carry a second phone radio against your skin while the first one sits in your pocket.

If what you want is your heart rate, your sleep and your daily activity — read on your wrist, kept on your device, with the least transmitting the job requires — then those extra four radios are not features you are using. They are just there, transmitting, and you are paying for them every month.

• One radio, Bluetooth Low Energy, measured at 0.91 mW — 0.09% of the FCC limit.
• No cellular modem and no Wi-Fi fitted, so there is nothing to switch off or trust us about.
• Readings processed on your device, never sold, and erasable in a single tap.
• $119.99 once — no subscription on any tracking feature, ever.
• FCC ID 2ASAU-S90, public, so none of the above depends on believing us.

So: an Apple Watch emits non-ionising radio energy from five radios, the heaviest rated to 200 mW. Whether that matters to you is your call, and we are not going to make it for you. But you should be able to see the numbers first — and now you know where they live.