Age Of Guinea Pig

[shannonandrosy]

I have had Rosey for about 2 months and Mona for about 1 month. Trying to guess about how old they might be. Rosey is 9 inches long and mona is 8 inches long. I dont have a scale to know how much They weigh. How old might they be?

 

[Swissgreys]

A scale is your best bet for determining age, and also keeping an eye on their general health and well being, so it might be a good idea to purchase a set.
I just use a set of regular kitchen scales with a cardboard box on top to hold the piggy.
Another good indicator is nails. Baby piggies (under 1 year) usually have very fine sharp nails and older piggies have thicker and sometimes curly nails.