Ok, so looking at the article for Bagan, and it says "Height: Unknown" and I thought "Strange. Let me look at some stuff to see what it could be." And so I did. I looked at how many pixels tall Super Godzilla was (Which was 84 pixels) and divided his official height, 110m, to find how tall each pixel was. So 110 Divided by 84 = 1.3.
So a pixel is 1.3 metres. Looking at Bagan's Sprite, I can see that he is 105 pixels tall, which would mean that it would be 1.3m X 105 = 136.5m. So as you can see, Looking at sprites and pixels, I can safely say that Bagan is 136/137 metres tall, but looking at other sources, He is 150m tall, which is a number that I think has never been given before, but Who knows.