Puto is one of the lightest kakanin because it is steamed and mostly air. A small 25g piece is about 40 calories: 30 from rice flour, 8 from sugar, 2 from coconut milk. Kawaling Pinoy's recipe card lists 1,421 calories for a batch of 3 dozen, which is 39 each. White King's boxed mix is listed at 100 per serving on FatSecret, which is about 2 to 3 pieces.
The toppings change it. A cube of cheddar on top adds about 15, so puto cheese is 55. Puto with a slice of salted egg is about 60. Puto pao, the big one stuffed with asado and a quail egg, is a different food entirely at about 180 each. Puto bumbong, the purple Christmas version with butter, sugar and grated coconut, is around 150 to 200 per stick depending on how much butter the vendor brushes on.
The count is the thing. Puto comes in packs of 10 to 12 for 30 to 50 pesos and a pack disappears during one episode of anything. Ten small puto is 400 calories, about the same as a rice meal but with no protein. With dinuguan, 3 puto is the usual side and adds 120 to a 330 calorie serving.