Based on the cartoons of my youth, my first image of giants was similar to;
"Typhon was a mixture of man and beast, the largest and strongest of all Ge's (Earth's) children. Down to the thighs he was human in form, so large that he extended beyond all the mountains while his head often touched even the stars.” (Apollodorus, Bibliotheca 1. 39)
Instead, Greek mythology presents the gods and giants in somewhat smaller form.
“She [Demeter] in the meantime went over to the threshold and stood on it, with feet firmly planted, and her head reached all the way to the ceiling.” (HH to Demeter 188-9, trans. Gregory Nagy)
“Aphrodite poured soft sleep upon Anchises, but herself put on her rich raiment. And when the bright goddess had fully clothed herself, she stood by the couch, and her head reached to the well-hewn roof-tree” HH to Aphrodite 170
I don’t don’t know how high the ceilings were in Mycenaean palaces and the huts of Trojan shepherds, but here in America our ceiling are 8ft. So the two goddesses are “8ft” in terms of human society, but even back then when the average man was 5.5, that’s not gigantic.
However, we are talking goddesses we can assume the “gods” were taller. How much?
Most vases portraying the blinding of Polyphemus make the son of Poseidon bigger than Odysseus but again not scrapping the stars.
So how much bigger than men were the gods and giants? I propose the Golden Ratio; 1.618 Just because it seems like something an Ancient Greek artist would do and because it seems to fit the ratio in the vase paintings. So;
5.5*1.618 = 8.9 ft tall deities and daemons
5.5ft in height, 1.5ft across the shoulders and waist, plus a foot thick = 8.25 cubit feet at 132 lbs. (I got sources for all this, but we are just estimating here.)
5.5*1.5*1 = 8.25 cubic feet at 132 lbs. for Ancient Greek guys
8.9*(1.5*1.618)*(1*1.618) = 34.9 cubic feet for the Ancient Greek gods.
Assuming the same density and simple math (rather than attempting the square/cubed law) the average Ancient Greek god weighed 558 lbs. So I propose the typical giants, cyclops, and Ancient Greek gods stood almost nine feet and weighed a quarter of a ton.