threads making

You MUST say what the thread series is and what % thread you want. The possible choices range from 6.700 mm to 7.366 mm.

This site can be quite useful sometimes.

There is a simple way to get the right size for the average application. Just take the diameter and subtract the pitch and you have a 77% thread. I personally like 75% threads, so I round up to the next size, but that's up to you. For example, if you have a 8M x1.25 thread, then 8mm - 1.25mm = 6.75mm which is 77% thread. If you round up to 6.80mm (which you are maybe more likely to have in your set), you get 74% thread.

The same thing works for American sizes. Say you have 1/4 - 20, then 0.25" - 1/20" = 0.200". There is no 0.200" drill, so round up to 0.201" and you have 75% threads.

Not as good as a chart, but you can always carry this in your head.