Sav & cage size?

[Kyle Barker]

I am curious how long my cage will hold my savanah. It is exactly 4'L, 2'H, 2'D. He/She is approx 18". Has sand on bottom, a retreat thats 2'W 18"D and 4"H. Also has a large water dish. and obviously lighting etc. Just wondering at what size will i have to move him/her into a larger cage. I also think its probably on the tall side, but oh well he can learn to climb .

Thanks for any help,