Near the same diameter but somewhat longer.
Wide 1 1/2"
High 2 1/4 as the mounting pin adds 1/4 ?
The motor itself is 2 3/4 long but then if you use the mount with the pin, it adds for a total of 4 1/4. Part of the value for me is that I can mount the suction cups and slide the motor on or when I like to fully hide it, I hollow out a chunk of wood and tuck the motor in without the mount. That can let me have wood sticking up in the center of the tank with the motor sucking water in a hole on one side, blowing out the other but totally hidden. Just an old holey "stump" sticking up. This lets me have some options and the cord can run to the top inside the wood so that it goes to the cover and then to the back of the tank.
These have the stop I mentioned built into the cover as a couple notches. When the 60 cycle hits at the wrong positive /negative, the impeller starts the wrong way but that makes it slide forward where the notches on it and the cover, stop the movement for the split second while the 60cycle goes the other direction. When that hits, the impeller is pulled down off the notches and starts turning the correct direction.
The problem I find is when I have really small stuff like Java moss bits that get wrapped around the shaft. it keeps the impeller from sliding forward. Kind of like it builds a "washer" of moss between the two sets of notches? It would not be a problem if I did not stop the power but I do that almost every water change. So when I see the circulation from a powerhead is gone, I pull the cover and pluck the moss off the shaft.
One of those little funny things that are easy to miss but all motors of this type do the same in some fashion.