It's a math calculation to get those steps/mm. You can usually work this out from the pitch of the threads, number of teeth, etc.
Those values are really "microsteps/mm" in most setups, as a single step pulse only advances the driver a single microstep (according to how many microsteps you've got configured using the jumpers - if that's full steps, then each pulse will be a full step).
So this means for a 1.8 degree motor (200 steps per revolution), you multiply that number by 16 if you're using 1/16th mcirostepping on the drivers, to get a full revolution. That means the board needs to send 3200 pulses to do a full revolution.
To take into account belts (usually for X & Y axes on a standard Prusa for example) or thread pitch (usually for Z on a standard Prusa) you need to calculate the effect they have on your steps (convert revolutions into distances, using whatever ratio the mechanism they use produces).
There's a calculator for these sorts of things here: [calculator.josefprusa.cz]
Those values are really "microsteps/mm" in most setups, as a single step pulse only advances the driver a single microstep (according to how many microsteps you've got configured using the jumpers - if that's full steps, then each pulse will be a full step).
So this means for a 1.8 degree motor (200 steps per revolution), you multiply that number by 16 if you're using 1/16th mcirostepping on the drivers, to get a full revolution. That means the board needs to send 3200 pulses to do a full revolution.
To take into account belts (usually for X & Y axes on a standard Prusa for example) or thread pitch (usually for Z on a standard Prusa) you need to calculate the effect they have on your steps (convert revolutions into distances, using whatever ratio the mechanism they use produces).
There's a calculator for these sorts of things here: [calculator.josefprusa.cz]