How fast do monitors grow?

Monitor lizards have no exact formula for growth rate . . . they tend to be all over the chart depending on gender (females smaller), age, variety, and so forth.

But, if you bought a newly-hatched Savannah monitor and kept it in good conditions, it might reach 18" to 20" in 6 months. Savannahs tend to reach peak growth at around 3ft to 4ft in length.