Simple fuel line question
 

I did a search and I could not find what I was looking for. I was just wondering how you measure fuel line. Is it the inside or outside diameter that you measure.

Thanks

Inside diameter

neopreme line is measured on the inside, metal line is measured on the outside.

thanks I was hoping for outside but now I know thanks again

I have steel line and mesured it was 3/8 on the outside so it is 3/8 or 5/16 or something else?

If it is 3/8" on the oustide how could it be 3/8" on the inside?

You have to allow for the thickness of the tubing.

sorry I might have worded that wrong, I was just told to run 3/8 fuel line and was wondering what I have now, and it is 3/8 on the outside

I can't say for sure if it is inside or outside diameter. I have always just run new line to start out with. I get aluminum line from the hardware store, and the flaring tool. I get the 3/8" flare nuts and call it good. It is cheap, easy, and aluminum is easy to work with.

Measurement is the inside diameter.