People sometimes ask why the same phone can be sold in the United States and in Europe but have different radiation numbers on its label. The short answer is that the two places use different ways of measuring how much radio energy the phone puts into your head.
The limit the FCC uses comes from 1996. It says a phone can put no more than 1.6 watts of radio energy per kilogram of tissue, averaged over any one gram of tissue. That number is called the specific absorption rate, or SAR. Every phone sold in the US is tested against it, and the test results are on file with the FCC under the device’s FCC ID.
Most of the rest of the world works from a different rulebook. The International Commission on Non-Ionizing Radiation Protection, or ICNIRP, puts out guidelines that many countries adopt. ICNIRP allows a higher headline number, 2 watts per kilogram, but it does the averaging over ten grams of tissue instead of one.
That ten-gram average changes things more than the simple difference between 1.6 and 2 would suggest. Averaging over a larger mass smooths out hot spots. A phone that creates a small patch of high exposure inside your head looks worse under the FCC method, because that hot spot is not diluted by the lower exposure in the surrounding tissue. Under the ICNIRP method, that same hot spot gets averaged into the cooler tissue around it and comes out looking lower. You cannot line the two numbers up directly. A phone that passes the FCC test might fail the ICNIRP test or the other way around, because the arithmetic is not the same.
The FCC looked at its limits in 2019 and decided to keep them. Groups that wanted stricter rules went to court. In 2021 a federal appeals court said the FCC had done a reasonable job on some questions, including whether the limits cause cancer. On other issues, such as the effect on children, the court said the agency had not explained its reasoning well enough and sent those matters back for another look. The court did not set new limits. So the 1996 numbers are still the ones in force today.
If you want to know how your phone tested, the FCC ID is printed on the device. You can look up its SAR number in the agency’s database. That tells you the phone met the 1996 limit when it was tested. It does not settle the larger health question. For information about health effects, talk to a doctor. For questions about what the rules mean, the FCC has public documents that explain its decisions.
For more on this, see FCC and ICNIRP limits compared.
