If you want to calculate wall studs distance as well as how many studs you need for certain lengths of walls, here are steps you can do considering this includes using vertical studs in between and there are the bottom plates and top plates. Remember that studs are generally positioned on 16-inch centers and this is calculated by taking the center lines of each stud:
Consider the length of the stud wall you want to create. Let’s say you want to build a 16-feet long wall stud.
Do the conversion. Start by multiplying 16 feet to 12 inches (12 inches = 1 ft) and you’ll get 192 inches.

Compute the gaps. Since you’ll need wall studs spacing of 16-inch gaps between each stud, divide the total length of the wall by 16 inches so 192/16 is 12 inches. Now, having 12 spaces in the wall also equals the number of studs you need which is also 12. Moreover, you should have an extra stud right at the end of the wall to where the cover board would be nailed so you still need to install a total of 13 studs.
Now, since the wall studs are vertically nailed for support, you may also need to install noggins in between the studs just for extra support. Noggins are used to support timber stud frames or to brace floors. Generally made of timber, some noggins are made of metals.