Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the human body when exposed to a radio frequency (RF) electromagnetic field, measured in watts per kilogram (W/kg). The SAR determines the amount of heat that is absorbed by human tissue, we must keep in mind that the longer you're on a call, the more heat is generated in our tissues.

SAR measurement is performed taking into account the use of smartphones when we speak (SAR head) and the body absorption rate (SAR body). For different variants of the same smartphone we will find different values, mainly due to network support, different frequencies, Single/Dual Sim models, etc.

There is no worldwide standard regarding the SAR measurement:
- In the United States, the Federal Communications Commission (FCC) requires a SAR level at or below 1.6 W/kg taken over the volume containing a mass of 1\_gram of tissue.
- In Europe, following IEC standards, the SAR limit is 2 W/kg averaged over 10 grams of tissue.
- India switched from the EU limits to the US limits in 2012, but the Indian government don't rely on SAR measurements provided by manufacturers, therefore, the Telecommunication Engineering Center (TEC) also performs these measurements.