I'm trying to figure out how much power, torque and rpm required for a motor to carry 2-3 kg (including his own weight). Also, the speed at which the weight is lifted doesn't really matter as much as just being able to lift the weight. I want to know what needs to be checked first to determine right set of motors to purchase.

  • \$\begingroup\$ Direct drive or geared? \$\endgroup\$
    – Solar Mike
    Commented Apr 19, 2022 at 7:27
  • \$\begingroup\$ It's a geared motor \$\endgroup\$ Commented Apr 19, 2022 at 7:33
  • \$\begingroup\$ Check out car seat motors - car seats can have a load of over 120kg (ie the passenger) and have gearing. Or check out wiper motors. Both will give you an idea. \$\endgroup\$
    – Solar Mike
    Commented Apr 19, 2022 at 7:36
  • 2
    \$\begingroup\$ Basically, if speed does not matter, any motor can lift any weight, with the right gearing. \$\endgroup\$
    – Klas-Kenny
    Commented Apr 19, 2022 at 8:17

1 Answer 1


Work done = force x distance. So for a given mass (in kg) the force required to lift it is 9.81 Newton per kg. Multiply this by the distance you want to lift it, in metres. That gives you the energy that you need to supply. Divide this by the time in seconds that you want to spend lifting the mass and that gives you the power that you need to provide. You should make allowance for some inefficiency in the gearing or whatever drive mechanism you’re using; thus could be 95% efficient but I’d lean towards the safe side and allow rather more, maybe twice the power you need. You know the speed (metres per second) at which you plan to lift the load. The motor speed, gear ratio and final drive can be chosen to provide the desired speed; for example the motor may run at 3600rpm (60 revolutions per second) with a 50:1 reduction winding a cord round a pulley of 25mm diameter, so the speed will be 60/50 x 25 x PI mm/s or roughly 94mm/s. As another example, the same motor abs reduction ratio driving a worm-and-track with 2mm pitch would lift 60/50 x 2mm per second = 2.4mm/s.


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