A baked potato has about 26 calories per ounce. I just assume that yukon gold potatoes are the same as any other non-sweet potato in terms of nutrition.
The small yukon gold potatoes that I get are about 3 ounces, so that's about 75 calories for one potato. In case you don't have a scale, I measured one of my potatoes so you can compare it to yours--it is about 2.75 inches long, 2 inches wide, and 6 inches in circumference (going around the short way, not the long way). It weighs about 2.75 ounces.