Motor Torque Conversion

Hello, I would like to convert the Torque of the iPower GBM4108H-120T Gimbal Motor to N•m (Newton metre).

However, the Torque of this motor is given in g (“Torque (g): 1200-1800”). Is this a valid unit for Torque, or should this mean gf•m (gram - force metre) or gf•cm (gram - force centimetre)?

If it is valid, how can I convert to N•m (Newton metre), please? Thank you very much.

Hi, I’m also confused by this torque unit, but this ‘solution’ is inaccurate.

Even if it’s related to this weird gram-force unit, then it would be equivalent to 0.00980665 N or 9.81 mN (milli-Newton, not Newton metre).

But gf this is a unit of force, not of torque, which is rotational and needs a length for describing the radius where the force is acting.

So if 1200 “g” actually means 1200 gf•m then this would convert to 1200 gf•m / 9.81 gf/mN = 122.3 mN•m = 0.122 N•m.
But it could also be 0.122 N•cm or 0.122 N•mm, which is 100 and 1000 times less.
Regarding this specific motor, looking at the other specs and its size, one can assume that 0.122 N•m could be a reasonable torque range.

So unfortunately the specs are unclear and you can only be sure by testing it yourself. But writing “Torque (g)” is simply wrong and confusing and should be punish- I mean corrected. The fact that there’s a whole wiki page dedicated to this imprecise and outdated unit speaks for itself…

Hello @technick thanks for your input,

You are correct, this is probably an error on the product listing. However, as this is a drone motor the spec is likely to be the “Thrust” which is usually in grams.

PS: I deleted my old post as it was probably incorrect

I’ve seen this “torque in g” at other places too, so yeah it must be coming from some kind of application.

Not trying to be pedantic, but thrust in grams would also be inaccurate, as it depends on voltage (rotation speed) and the type of the attached propeller. But actually this is a gimbal motor which is quite the opposite of a drone motor (slow, strong, high resistance).

It’s actually quite hard to find an indication of nominal torque for gimbal and drone BLDC motors, even the manufacturers don’t seem to specify it explicitly, which is unfortunate if you want to use it in your own application or as a generic motor.

The manufacturer of that motor offers lots of different motors, mostly for drones, if you look for drone motor charts you’ll often see Thrust using the G unit. I know it can be misleading because it is not actually thrust but it is what it is.

However, if you’d like more accurate specifications you can always ask the manufacturer directly at [email protected]