Here is the uncomfortable truth most pet stores will not tell you: the guinea pig cage on their shelf is usually too small. Rescue groups and humane societies recommend around 7.5 square feet of floor space for a single pig and more for a pair, and most commercial cages do not come close. Bigger is always better, and a two-by-four grid-style cage is the budget favorite for a reason.
The floor and the bedding
Wire floors are out: they hurt toes and feet. You want a solid bottom with paper-based bedding, an inch or two deep. Skip cedar and pine shavings; the aromatic oils irritate small lungs. Spot clean daily and do a full bedding change at least weekly.
Where the cage lives
Indoors, out of drafts and direct sun, steady between about 65 and 79 degrees. Guinea pigs also want to be near the action: a quiet spare room is actually worse for them than the family room, because they are herd animals and the sound of the household is their entertainment.
What goes inside
Unlimited timothy hay is the single most important item in the cage; it is food, dental care, and bedding enrichment all at once. Add a ceramic or bolted water bottle, a heavy food dish, at least one hideout per pig, and safe chew items. Hideouts matter more than they look: a guinea pig without a place to hide is a stressed guinea pig.
The daily vitamin C most new owners miss
Guinea pigs cannot make their own vitamin C, the way humans cannot, so it has to arrive fresh every day. Bell peppers, parsley, and a slice of orange all work, or a supplement. This is the deficiency behind most “my pig seems tired” vet visits, and it is the cheapest problem on this list to prevent.
And get two, if you can. A single guinea pig is a lonely guinea pig no matter how attentive you are, and a bonded pair does not cost double the work, only double the hay.