Tango's 2 1/2, years old, 3.9 lbs. He gets fed twice a day, just a tad under one quarter cup each feeding, for a total of almost 1/2 a cup a day. If I've been doing a lot of training, and giving him treats, then he gets less. He's at a perfect weight.
Jazz is still a puppy, and smaller than Tango for the moment. She's 2 1/2 lbs right now. I give her the same amount as Tango. She's lost the big puppy belly, and now is quite lean, and very healthy. I'll adjust her intake as she grows. For the moment, the amount seems to be right for her, though I watch closely to make sure she's not packing on any extra weight. I've been thinking of cutting back Tango just a bit, because about half the time he doesn't quite finish all his food, which tells me he doesn't need it.