The average guinea pig life span is around 4-6 years, although some can live as long as 8 years. This is much longer than most other small pets, including other rodents such as mice (1-3 years), gerbils (2-4 years), and hamsters (2-3 years).
Your guinea pigs' life span will depend on a number of factors, such as how well they are cared for, their diet, and whether they suffer from any serious illnesses during their life. Having said that, there is only so much you can do to lengthen your cavy's lifespan, and even the most well cared for pet may die young through no fault of the owners.
The best advice is to enjoy every minute you have with your pet, so that you have many happy memories to look back on after they pass away.
Because guinea pigs live for so long, you should take this into account when deciding whether they are the right pet for you. Remember that you will need to feed them and give them water every single day during that time, and you will also have to play with them and clean out their cage frequently. If this sounds like too much of a commitment then you might be best off considering another animal which does not live so long, and which will place less demands on your time.
If you are thinking about buying guinea pigs for your children, you need to think about whether they will still want to care for them 1, 2, or 5 years down the line. Young children in particular can be very fickle, and you may soon find that they lose interest in their cavies, leaving you with the responsibility of looking after them.
You must also consider who will look after your pets when you are away on holiday. Guinea pigs are relatively undemanding animals, but they still require daily care and attention, so it important that you know somebody who can care for your pigs when you go away, and provide them with the appropriate level of care. If you don't know anybody who can fill this role, you might consider joining your local guinea pig club, where you can meet other owners, and arrange to look after each others' pets.
Despite these important considerations, a guinea pig's long life span is really a blessing. Provided you can fulfil your cavy's needs for its whole life, you will be able to spend many happy years getting to know your pets and forming a special relationship with them.