You can make an approximate calculation of the pitch by laying the prop on a good flat surface, supported by the hub with the blade face ( pressure side) up. Measure the angle between the flat surface and the blade face about 75% of the blade length distance out from the hub. Plot this measured angle on a large piece of paper and extend the lines out a distance equal to the circumference of the 75% blade length circle.
The distance between the two plotted lines at this point will be very close to the pitch of the propeller
, because this distance represents the distance which the propeller
blade would "screw" itself thru the water
if there was no slip.
A more productive method might be to take the prop to a decent propeller shop. They can measure the pitch accurately with a prop scan machine or pitch blocks, and they can also check that it is really a 1 inch shaft with American taper or a 25 mm shaft with metric taper.