What SAR tells you. And what it leaves out.
Understand head SAR, body SAR, simultaneous transmission, and why a laboratory rating is not a personal exposure meter.
A phone specification can tell you how large a screen is. A SAR result answers a narrower question: how much radiofrequency energy was absorbed per kilogram under a particular laboratory test condition?
Start with the test, not the color
Specific absorption rate is expressed in watts per kilogram (W/kg). Our US comparison cells use values reported in RF Safe’s database against the FCC’s localized 1.6 W/kg limit averaged over one gram of tissue. European head and body values generally use a different ten-gram averaging method and a 2 W/kg limit. Those two test systems should not be mixed in a single ranking.
Head, body, hotspot, and simultaneous-transmission values represent different use configurations. A simultaneous value may include more than one transmitter operating together. These are separate reported results; do not add the head and body numbers together or interpret their difference as an exposure reduction you will experience.
A comparison aid, not a health score
Our colors make differences within the same measurement easy to see. They do not label a phone safe or unsafe. Zero and missing values are shown as unavailable, rather than receiving a favorable color. A lower listed maximum does not guarantee lower everyday exposure: power control, reception, data traffic, distance, positioning, and active radios all matter.
Check the exact model
Use the comparison to ask better questions, then pair it with practical habits: more distance, less unnecessary transmitting time, and wired connections when practical.
Original: cellularphones.org