Sounds to me like a resolution value in the cutter configuration! Normally with American and Japanese plotters the resolution is 1016 but some for some Chinese plotters this value needs to be adjusted to higher or lower depending on how much your off the correct size and this is exceptional for plotters with stepper motors! 1016 value is the number of steps the motor moves the carriage to equal an inch this could also be in centimeters or millimeters so do the conversion math! Plotters equipped with servo-motors this is hardly never the case! Good Luck! In your case you may need to increase the resolution value.