Regulators require phone makers to publish SAR figures. They do not require it for wearables, so the numbers exist but are scattered across manufacturer documentation and regulatory filings.
Electromagnetic field. The invisible energy every wireless device gives off. It's the broad category, not a score — measured in the air around a device, in V/m or W/m².
Specific Absorption Rate. How much of that EMF your body actually absorbs, in watts per kilogram. This is the number on the spec sheet, and the one worth comparing.
Two authorities, not measurements. Both use SAR; each sets its own maximum. The FCC governs the US and Canada, ICNIRP the EU and most of the world.
In one line: a device emits EMF → your body absorbs some of it → that absorbed amount is measured as SAR → the FCC and ICNIRP each cap how high the SAR may go.
| Where the device sits | Max SAR allowed by FCC (US & Canada) | Max SAR allowed by ICNIRP (EU & most others) |
|---|---|---|
| Head or against the body Phones, chest-worn monitors, pendants |
1.6 W/kg averaged over 1 gram |
2.0 W/kg averaged over 10 grams |
| Wrist, hand, ankle or ear Smartwatches, trackers, hearables |
4.0 W/kg averaged over 10 grams — the extremity limit |
Higher allowance applies to limbs than the 2.0 W/kg local limit |
Two further ICNIRP notes: whole-body exposure is averaged over 30 minutes (raised from 6 in the 2020 revision, to match how long body temperature takes to rise), and above 6 GHz the standard switches from SAR to absorbed power density — increasingly relevant as 5G bands climb.
The comparison trap. A smartwatch's SAR figure is usually measured against the 4.0 W/kg extremity limit, while a phone's is measured against 1.6 W/kg for the body — and the FCC averages over 1 gram while ICNIRP averages over 10. Four numbers, four different yardsticks. Every figure in the ViaMondo index is published with its standard, its averaging mass and its test position attached.
Both thresholds sit roughly 50× below the exposure level that produces measurable tissue heating under controlled conditions. The margin is built in.
Wearables transmit at far lower power than handsets — Bluetooth especially. Most sit well under the limits. The trade-off worth knowing: they're worn continuously.
No causal link has been established between low-power RF from wearables and long-term harm. The WHO's Group 2B "possibly carcinogenic" classification rests on mobile phone research, not wearables.
Because you asked, and because the data should be easy to find. We report measured figures and the standards behind them — and we don't sell fear, or shielding products.
Our position. We compile published SAR figures for the devices we cover and list them alongside the applicable limit, so you can compare like with like. The figures are the manufacturers' and the regulators', not ours — our work is finding them, citing them and explaining what they mean. We report the scientific evidence as it stands rather than as either side would prefer it. If a device's SAR is unusually high for its class we'll say so — and if the evidence doesn't support a health concern, we'll say that too.