Mice are omnivores that eat seeds, grains, insects, fruits, and vegetation. In the wild, they forage for whatever is available and calorie-dense. In homes, they’ll nibble on practically anything from cereal to cardboard. What a mouse eats depends largely on where it lives and what it can find.
What Wild Mice Eat
Seeds and grains form the core of a wild mouse’s diet. In preference tests, house mice consistently favor small, high-energy seeds like canary seed, oatmeal, and wheat. Beyond grains, wild mice eat insects, larvae, fruits, roots, and leafy vegetation. They’re true opportunists: a field mouse might eat grass seeds and beetles one day, then raid a bird feeder the next.
This flexibility is a big part of why mice thrive on every continent except Antarctica. They don’t specialize. If something is edible and small enough to carry, a mouse will try it.
What Mice Eat in Your House
House mice living alongside humans eat whatever you leave accessible. Cereal, rice, pasta, bread, crackers, pet food, birdseed, and pantry staples are all fair game. Mice are particularly drawn to foods high in protein and fat, which is why peanut butter is one of the most effective bait foods (and a genuine mouse favorite, far more than cheese).
The cheese myth is one of the most persistent misunderstandings about mice. A house mouse will eat cheese if nothing better is around, but it’s not a preferred food. Mice gravitate toward grains, seeds, and calorie-dense spreads like peanut butter instead.
Mice in homes don’t limit themselves to food, either. They gnaw through packaging, cardboard, soap, candle wax, and even electrical wiring. This chewing isn’t about hunger. Mice have incisors that grow continuously, and gnawing keeps them filed down. They’ll chew through lead, cement, and plastic if the material is in their path, which is why rodent damage to wiring is a documented cause of house fires.
How Much Mice Eat and Drink
A mouse eats roughly 3 to 5 grams of food per day, which is a surprisingly small amount (picture a level teaspoon). But relative to body weight, that’s significant for an animal weighing only 20 to 30 grams. Mice nibble in many small meals rather than eating large portions at once, typically visiting food sources 20 or more times in a single night.
Water intake averages about 5 to 6 milliliters per day, roughly one teaspoon. Some strains drink as little as 4 ml and others closer to 8 ml. Mice can get a portion of their water from moist foods, which is why they sometimes survive in dry environments like grain silos where standing water isn’t available.
Food Hoarding Behavior
Mice don’t just eat on the spot. They carry food back to their nests and stockpile it in what researchers call “larder hoards,” small caches stored near their sleeping area inside a wall, burrow, or hidden corner. This secures a food supply for times when leaving the nest is dangerous, such as when a predator is nearby or during cold weather. If you find small piles of seeds, kibble, or crumbs tucked behind appliances or inside wall cavities, you’re looking at a mouse pantry.
Nutritional Needs
Mice need a diet that’s roughly 18 percent protein, 5 to 10 percent fat, and around 7 percent fiber. These ratios keep them healthy, growing, and able to reproduce. Too much fat (above 40 percent of the diet) actually slows growth, and too much fiber reduces overall performance by filling them up without providing enough calories.
Pregnant and nursing mice need the higher end of those protein and fat ranges. Diets with about 18 percent protein and 10 to 11 percent fat support healthy litter sizes of six to seven pups. A high-fat, high-sugar diet during pregnancy, similar to a typical Western diet, has been shown to increase mortality in newborn mice, which matters for anyone breeding pet mice at home.
Feeding a Pet Mouse
Pet mice do best on a base diet of commercial seed mix or pellet food designed for mice. For two to three mice, about two tablespoons of seed mix per evening covers their needs. Supplement this with fresh vegetables once a week, roughly one tablespoon’s worth.
Safe vegetables include broccoli, carrots, peas, cabbage, Brussels sprouts, celery, bok choy, parsley, tomatoes, and lettuce. For fruit, apples, pears, bananas, and plums are all safe options, but fruit is high in sugar, so treat it as a small daily snack rather than a dietary staple. A thin slice of apple or a small piece of banana is plenty.
Fresh water should always be available in a sipper bottle. Even though mice don’t drink much, dehydration is dangerous for an animal this small.
Foods That Are Harmful to Mice
Chocolate, caffeine, and raw beans are toxic to mice. Citrus fruits can cause digestive upset in males specifically. Sticky or hard candies pose a choking risk. Processed human foods with high salt, sugar, or artificial additives aren’t immediately lethal but cause health problems over time, including obesity and liver damage. If you’re keeping pet mice, stick to whole, unprocessed foods and purpose-made mouse feed.