The gear reduction in a right-angle worm drive would depend on the amount of threads or “starts” on the worm and the number of teeth on the mating worm wheel. If the worm has two starts and the mating worm wheel has 50 tooth, the resulting equipment ratio is 25:1 (50 / 2 = 25).
Calculating the gear ratio in a planetary equipment reducer is much less intuitive since it is dependent on the amount of teeth of sunlight and band gears. The planet gears become idlers and do not affect the apparatus ratio. The planetary equipment ratio equals the sum of the number of teeth on sunlight and ring equipment divided by the amount of teeth on the sun gear. For instance, a planetary established with a 12-tooth sun gear and 72-tooth ring gear includes a gear ratio of 7:1 ([12 + 72]/12 = 7). Planetary gear pieces can achieve ratios from about 3:1 to about 11:1. If more equipment reduction is needed, additional planetary stages can be used.
If a pinion gear and its mating gear have the same quantity of teeth, no reduction occurs and the apparatus ratio is 1:1. The gear is called an idler and its own main function is to change the path of rotation Planetary Wheel Drive rather than decrease the speed 
or raise the torque.
Parallel shaft gearboxes many times contain multiple gear models thereby increasing the apparatus reduction. The full total gear decrease (ratio) is determined by multiplying each individual equipment ratio from each equipment arranged stage. If a gearbox consists of 3:1, 4:1 and 5:1 gear sets, the total ratio is 60:1 (3 x 4 x 5 = 60). In our example above, the 3,450 rpm electric electric motor would have its velocity reduced to 57.5 rpm by using a 60:1 gearbox. The 10 lb-in electric engine torque would be risen to 600 lb-in (before effectiveness losses).