The step angle of the motor depends on the requirement of the load precision. The minimum resolution (equivalent) of the load is converted to the motor axis, and how many angles (including deceleration) should be taken for each equivalent motor. The step angle of the motor should be equal to or less than  this angle. The step angle of the stepping motor in the market is usually 0.36 degrees /0.72 degree (five phase motor), 0.9 degree /1.8 degree (two, four phase motor), 1.5 degree /3 degree (three phase motor) and so on.