What part of a 1" sensor is 1"

[Al Bany]

How is the 1" sensor on my P4P measured?

 

[Meta4]

How is the 1" sensor on my P4P measured?

No part measures one inch.
The dimensions are approx. 13.2mm x 8.8mm

Sensor sizes are named in a very confusing way
Manufacturers of compact digital cameras have long used a rather ambiguous way to define the sizes of the sensors in their products.
The system used dates back to video camera tubes used in the 1950s, with the ‘inch’ measurement referring to the outer diameter of the video tube. This system has no relationship to imager sizes

 

[jephoto]

Isn’t it the diagonal o of the sensor- i.e. lower left corner to upper right?

 

[sar104]

Isn’t it the diagonal o of the sensor- i.e. lower left corner to upper right?

That would be a logical way to measure sensors but no - it doesn't mean that at all. If you want to take a look at the plethora of sensor size names, the Wikipedia page is quite informative:

https://en.wikipedia.org/wiki/Image_sensor_format

 

[Al Bany]

Wow, plethora is right! I had no idea. According to the chart a 1 inch sensor is only 5/8 of a inch measured diagonally.

 

[With The Birds]

Wow, plethora is right! I had no idea. According to the chart a 1 inch sensor is only 5/8 of a inch measured diagonally.

According to reality that’s what it is.

 

[jephoto]

So.... where does the 1” come in???

 

[jephoto]

Never mind. Read the Wikipedia thing. Oy!

 

[Al Bany]

This guy has a pretty good explanation that goes along with what Meta4 says above.
one-inch-sensor.htm

 

[With The Birds]

Never mind. Read the Wikipedia thing. Oy!

And- you could have read the thread- the answer is there...