Why is Gotenks bigger than Goten and Trunks?

[George]

Goten And trunks are both very small. But when they fuse to Gotenks, they become much bigger and taller, like tripling their size, just about as big as the adults.
But both Gogeta and Vegito is just about the same size as Goku and Vegito.
Then why is gotenks so big?

 

[david]

Well for a couple reasons....

1.) It's a tv show so they do whatever the heck they want.

2.) Because it makes Gotenks look much more bad ass.

3.) If they made Gogeta bigger than Goku, he'd just look silly.