1 inch how many thread?
So when you measure one inch, like in this case here, you will see: 1-2-3-4-5 in that one inch. So when you read a bolt that says 1/4″-20 x 2″, that means, 1/4″ inch diameter, 20 threads TPI that's threads per inch, which would be here,and then 2 inches long.