A full grown guinea pig varies in size depending on their gender and also their breed. Generally speaking guinea pigs roughly range from 10-12 inches (25.4 - 30.5cm) in length and weigh between 1.5 - 2.6 pounds (700 - 1179 grams). Trying to differentiate a male and female guinea pig based on their weight or size may be tough, so consider distinguishing them based on their genital area, if that’s something you’re trying to do.
To compare, hamsters (dwarf) grow to around 2-4 inches (5.5-10.5cm) long, which may be equivalent to a baby guinea pig. If you'd like to know more about the difference of guinea pigs and hamsters read our other blog post!
Measuring Guinea Pigs
To measure your guinea pigs lay out a tape measure and try to place your guinea pig parallel to the tape. The measurement should be taken from the tip of the guinea pig’s nose to its rear!