There are several things that could cause this. Scaleing, G-code, Motor tuning, ect. I would guess it is your steps per in motor tunning right now. I have pasted in something I hope will help.

Here is how you do the math. I will give you mine as an example. What we need to know is, How many pulses from Mach will it take to move the machine 1 of your units? (inch,mm) Mine is in inches. 1 inch = 10,000 pulses on mine. This is how I came up with the number.

My steppers have 200 pulses per revolution. ( 360 degrees divided by 1.8 degrees = 200 )

Micro stepping = 10. So 200 X 10=2,000

Motor to screw gearing is 1-1. So 2,000 X 1=2,000

Screw lead is .200 of an inch. My screw will have to turn 5 rounds to move the nut 1". 1.0 divided by 0.200=5. So 2,000 X 5=10,000.

Brett