Is there any chance there´s a caliper and AN3 fitting or hose in front of you right now?
And most important, would you like to measure the ID? Millimeter would be great.

 

I believe they go by 16th of an inch so 3/16 = .1875 inchs = 4.762 mm

 

When I tried to Google this some people said that 3/16 was the OD of the hose. Seems a bit tiny, you might be right here.

 

Partly, the manufactures really measure it by OD, but some measure over the braid and some dont. Which is a pretty dumb way to measure the hose, if you ask me.

The actual ID of a #3 hose according to aeroquip, is .14.

 

Thanks, great info! If you make a guess, how much smaller do you think the fitting might be since it´s pushed into the hose?

 

What type of fitting? Are you using AN fittings or like push lock hose?

What are you using this #3 line on, brake lines?

 

Most people use AN3 hoses with AN fittings for oil supply to the turbo, just trying to find out how the sizes in mm.
Want to know the ID at it smallest spot, should be in the fitting.

(Sorry for bad technical English, Swedish dude...)