How do you know what age your guinea pig is?

< 1 month 100-200 grams

1-2 months 220-350 grams

3-4 months 350-500 grams

4-6 months 550-700 grams

6-12 months 800-1000 grams

1-2 years 1000-1200 grams

2-4 years 1200-1400 grams

4-8 years 1400-1600 grams

8+ years 1600+ grams