SAR stands for Specific Absorption Rate is the unit of measurement for the amount of Radio Frequency energy absorbed by the human body when using a mobile phone. SAR value is expressed as a measure of the maximum energy absorbed by a unit of mass of exposed tissue of a person using a mobile phone, over a given time or more simply the power absorbed per unit mass.
SAR values are usually expressed in units of watts per kilogram (W/kg) in either 1g or 10g of tissue. Every country has a regulatory threshold value of SAR for mobile phone devices. In India the regulatory unit being 1.6 W/kg.
Although the SAR is determined at the highest certified power level in laboratory conditions, the actual SAR level of the phone while operating can be well below this value. This is because the phone is designed to use the minimum power required to reach the network. Therefore, the closer you are to a base station, the more likely it is that the actual SAR level will be lower.