This free guinea pig food calculator works out exactly how much to feed your guinea pig each day — hay, fresh vegetables, pellets, water and vitamin C — by the number of pigs and their life stage. It is built on the vet-recommended 80% hay, 15% veg, 5% pellets diet.
A healthy adult guinea pig eats unlimited hay, about 1 cup of fresh veg, and just 1/8 cup of pellets a day — far fewer pellets than most owners give. Enter your pigs below for exact portions.
How much hay, veg, pellets and water your guinea pigs need each day.
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fresh veg per day
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Hay
80% of diet
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Pellets
1/8 cup each
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Water
Per day
Estimate daily calorie needs from your guinea pig’s weight.
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daily calorie needs
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Body weight
Entered
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Formula
Metabolic
~80%
From hay
Not pellets
Daily fresh-veg amount and the vitamin C your guinea pigs need.
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fresh veg per day
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Vitamin C
Daily total
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Per pig
Fresh greens
Low calcium
Best greens
Daily
A simple daily feeding routine for your guinea pigs.
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daily routine
The ideal guinea pig diet ratio, at a glance.
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daily diet ratio
How the Guinea Pig Food Calculator Works
The guinea pig food calculator builds each day’s portions from the vet-recommended ratio of 80% hay, 15% fresh vegetables and 5% pellets. For one adult guinea pig that means unlimited grass hay, about 1 cup of fresh leafy greens, and just 1/8 cup (roughly 18 g) of plain vitamin-C-fortified pellets a day, plus 80–120 ml of fresh water and daily vitamin C. The calculator multiplies the veg, pellet and water amounts by the number of pigs and adjusts the hay type and pellet amount for life stage — alfalfa for pups and pregnant sows, timothy for adults and seniors.
Food
Per adult pig / day
Share of diet
Notes
Grass hay
Unlimited, 24/7
~80%
Timothy, orchard or meadow
Fresh veg
~1 cup
~15%
Mostly low-calcium leafy greens
Pellets
1/8 cup (~18 g)
~5%
Plain, vitamin-C-fortified
Water
80–120 ml
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Fresh daily; bottle or heavy bowl
Guinea pigs cannot make their own vitamin C, so they need about 10–30 mg a day (more if pregnant or ill) from fresh veg or fortified pellets — without it they develop scurvy.
The Perfect Guinea Pig Diet (80 / 15 / 5 Chart)
The chart below shows the ideal daily diet split. Hay dominates at about 80% and should never be rationed; fresh veg makes up around 15%; and pellets are a small 5% top-up, not the main meal.
How Much Food Do Guinea Pigs Need Per Day?
An adult guinea pig needs unlimited grass hay, about 1 cup of fresh vegetables, and roughly 1/8 cup (about 18 g) of plain pellets every day, plus constant fresh water. Hay is the single most important food — it should always be available and makes up about 80% of what they eat. The pellet portion surprises most owners: it is much smaller than a typical scoop, because over-feeding pellets leads to obesity and leaves less room for the hay that keeps their teeth and gut healthy. Two guinea pigs need double the veg, pellets and water; the hay stays unlimited.
What Is the 3-3-3 Rule for Guinea Pigs?
The 3-3-3 rule is a settling-in guideline, not a feeding rule — it is often confused for one. It describes how long a newly adopted guinea pig takes to adjust: about 3 days to decompress and feel safe, 3 weeks to learn the routine and start showing its personality, and 3 months to feel fully at home and bonded. During those first days keep feeding simple and consistent — unlimited hay, fresh water, and the veg and pellets it is used to — and introduce any new vegetables slowly to avoid upsetting its digestion. So while the 3-3-3 rule is about behaviour and bonding rather than portions, steady feeding is a big part of helping a new piggy settle.
What Is the Perfect Diet for a Guinea Pig?
The perfect guinea pig diet follows the 80 / 15 / 5 rule: about 80% grass hay, 15% fresh vegetables, and 5% pellets, with fresh water and daily vitamin C alongside. Unlimited timothy, orchard or meadow hay forms the base (pups and pregnant sows get alfalfa instead for the extra calcium). Fresh low-calcium leafy greens provide vitamins and variety, a small measured portion of plain fortified pellets rounds out the nutrients, and a vitamin C source every day prevents scurvy. Get that balance right and you cover almost everything a healthy guinea pig needs.
What Should I Feed My Guinea Pig?
Feed unlimited grass hay, a daily cup of fresh leafy greens, a small portion of plain pellets, and plenty of fresh water. Good daily vegetables include romaine and leaf lettuce, coriander, and bell pepper (rich in vitamin C); rotate others like cucumber and courgette a few times a week. Just as important is what not to feed: no iceberg lettuce, no dairy, meat, bread, cereal, chocolate, or sugary treats, and only small amounts of high-calcium greens (spinach, kale, parsley) and fruit. Any diet change should be gradual, because a guinea pig’s gut is sensitive and a pig that stops eating needs a vet urgently.
Frequently Asked Questions
What vegetables can guinea pigs eat every day?
Daily-safe, low-calcium greens include romaine lettuce, red and green leaf lettuce, coriander (cilantro), and bell pepper, which is an excellent vitamin C source. Aim for about a cup of mixed greens per pig a day. Rotate in cucumber, courgette and a little carrot top a few times a week, and keep high-calcium greens like spinach, kale and parsley occasional.
How much hay should a guinea pig eat?
As much as it wants — hay is unlimited and should be available 24/7. A rough guide is that a guinea pig eats roughly its own body size in hay each day. Never ration hay to make room for pellets or veg; it is about 80% of the diet and essential for wearing down their continuously growing teeth and keeping the gut moving.
Do guinea pigs need pellets, or just hay and veg?
Pellets are helpful but secondary. A good plain, vitamin-C-fortified timothy pellet fills small nutritional gaps, but only about 1/8 cup per pig a day. Too many pellets cause obesity and crowd out hay. Choose uniform plain pellets, not muesli-style mixes with seeds and coloured bits, which let pigs pick out the unhealthy pieces.
Why do guinea pigs need vitamin C every day?
Unlike most animals, guinea pigs cannot produce their own vitamin C, so they must get about 10 to 30 mg a day from food (more if pregnant or ill). Without it they develop scurvy, with signs like a rough coat, swollen joints, reluctance to move and loss of appetite. Bell peppers and fortified pellets are reliable sources; a vet may suggest a supplement for a pig that is unwell.
What foods are dangerous for guinea pigs?
Never feed dairy, meat, eggs, bread, cereal, grains, chocolate, nuts, seeds, or anything sugary or processed. Avoid iceberg lettuce (little nutrition, can cause diarrhoea), potato, onion, garlic and rhubarb. Most fruit should be only an occasional treat because of the sugar. Introduce any new vegetable in a small amount, as sudden diet changes upset their digestion.
How much should I feed a baby guinea pig?
Pups under about 6 months need unlimited alfalfa hay (plus grass hay) and alfalfa-based pellets for the extra calcium and protein they need to grow, rather than being rationed. Introduce fresh vegetables gradually in small amounts so their gut adjusts. At around 6 months, transition them onto timothy hay and adult timothy pellets.
This guinea pig food calculator follows the widely recommended 80% hay, 15% fresh vegetables, 5% pellets diet, with roughly 1 cup of veg and 1/8 cup (~18 g) of plain fortified pellets per adult pig per day, 80–120 ml of water, and 10–30 mg of daily vitamin C (more for pups, pregnant or ill pigs, who also get alfalfa hay). These are general guidance, not veterinary advice; a guinea pig that stops eating, or is losing weight, needs a cavy-savvy vet promptly.
