how do I calculate thread pitch or TPI?

My lathe is metric, which is not a problem to me as I grew up with
metric. If someone could show me the math to convert the information
below, that would be great.



I don't really know what thread pitch is, but I know threads per inch.



Here's the information I do know.

- 1 complete turn of the acme screw moves 0.20 cm, or 2 mm. And that's
about all I know from my lathe.

- So it takes 5 turns of the hand wheel to move 1 cm.

- As there is 2.54 cm in 1 inch, thus somehow I calculate my acme screw
to be 12.7 TPI. is this correct?



Also, what is pitch, and how do I calculate it from the TPI?



Thanks.



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