Guinea pigs are best kept as indoor pets.

Guinea pigs are social and talkative little animals, and become more trusting and friendly when in contact with you.  Keeping them inside strengthens the human-animal bond and allows you to have a more interactive relationship with them.
Most guinea pigs don’t jump or climb so the sides of the enclosure need only be at least 30 cm high. The bare minimum size for a guinea pig cage is 0.7m x 1m, which really is only suitable for sleeping or resting.

The ideal floor for the guinea pig is solid, slip-free, with soft and dust free bedding (such as grass hay, shredded paper or towels) provided. If there are ramps and second storeys make sure that their feet and nails cannot get caught between metal rungs. Also make sure that they can’t fall down. It is difficult to toilet train guinea pigs and it is best to offer hay in the largest tray you can to making cleaning easy. Hay and bedding should be changed daily for hygienic reasons and to control urine and faecal odour.

Guinea pigs love to hide and providing them with little hide-away places and furniture such as tunnels or tubes are essential. Tunnels and tubes (four inch or larger PVC pipe, elbow joints and T joints) can be easily obtained from hardware stores. Guinea pigs can hide and run through and play in them. They are chew proof and easy to clean. You can also add rocks and bricks to their cage to provide surfaces to wear down their claws and to stimulate their sense of adventure.

If your guinea pig is kept outside, make sure they are safe from predators (dogs, cats, foxes, birds).

Do not keep guinea pigs in metal hutches outside. These heat up easily in warm or hot days even when in the shade. Guinea pigs are very susceptible to heat stroke. It is important to move your outside guinea pigs indoors when temperatures exceed 28 degrees.