The killjoys at dxomark.com have put the iPhone 6s through its paces and its camera scores the same overall as the iPhone 6’s camera. More megapixels from a sensor of the same physical size turn out not to be useful.
The top-performing camera phone, according to dxomark, is the Sony Xperia Z5, which has a 1/2.3″ sensor. This corresponds to 6.3×4.72mm (about 30mm^2). Apple relies on a 1/3″ sensor, 4.8×3.6mm in size (17mm^2). Thus the Sony has roughly twice the sensor area.
Readers: Who has traded an iPhone 6 for a 6S? How does the real-world camera performance compare?
I am not clear why you can typeset an inch symbol and a multiplication symbol but not a superscript 2 (mm²).
Further, I am not sure about the units you are using in sensor dimensions. Apple’s sensor is exactly one-third of an inch?
Joe: See https://en.wikipedia.org/wiki/Image_sensor_format for an explanation of why sensor sizes are express in inches: “Sensor sizes are expressed in inches notation because at the time of the popularization of digital image sensors they were used to replace video camera tubes.”