Guinea pig food calculator

How it works

Per group per day = amount per animal per day x animals, for each of hay, pellets and fresh vegetables. Per month = per day x 30.44 days (365.25 / 12). Bags per month = amount per month / bag weight, shown exact and rounded up to what you buy. One bag lasts = bag weight / amount per group per day. Cost per month = bags per month (exact) x the price of a bag, plus vegetables per month x their price per weight; the total adds the lines that have a price and says which ones do not.

Hay is unlimited for a guinea pig: it is most of the diet and keeps the teeth and gut working. The hay figure is what one animal typically gets through, for the shopping list, not a ration to measure out. Guinea pigs cannot make vitamin C and need about 30 mg a day per animal (Feeding (updated 14 Aug 2026), 2026-09-19), which is why fresh vegetables and pellets made for guinea pigs (not rabbit pellets) are on the list; the calculator shows the figure as information and does not compute it.

Every number is yours to change; the starting values only save typing. There are no live prices. All calculations run in your browser and the inputs stay there, so the Pro plan can pick up your animals.

Sources of the US starting values

• Body weight: Merck Veterinary Manual, table Physiological Data for Guinea Pigs (undated): adult sows 700-900 g, boars 900-1,200 g; 0.9 kg, where the two ranges meet, is the starting weight — https://www.merckvetmanual.com/multimedia/table/physiological-data-for-guinea-pigs, read on 2026-09-19
• Hay: Hay is unlimited; for the shopping list: Vethope veterinary clinic (Prague), Nutrition of guinea pigs (19 May 2025): an adult 1 kg guinea pig eats about 70 g of food a day, hay 70-80 % = 49-56 g; midpoint 52.5 g per kg x 0.9 kg = 47.3 g. Consistent with Merck Veterinary Manual, Management of Laboratory Animals (Dec 2025): animals eat at least 4-6 % of body weight a day, and PDSA (Oct 2024): hay and grass are 85-90 % of the diet — https://www.vethope.cz/en/nutrition-of-guinea-pigs/ and https://www.merckvetmanual.com/exotic-and-laboratory-animals/laboratory-animals/management-of-laboratory-animals and https://www.pdsa.org.uk/pet-help-and-advice/looking-after-your-pet/small-pets/your-guinea-pig-s-diet, read on 2026-09-19
• Pellets: Vethope veterinary clinic (Prague), Nutrition of guinea pigs (19 May 2025): an adult 1 kg guinea pig eats about 70 g of food a day, pellets 10 % = 7 g per kg; x 0.9 kg = 6.3 g. Volume guides agree it is a small amount: PDSA, Your guinea pigs' diet (Oct 2024): one tablespoon per adult guinea pig a day; Merck Veterinary Manual, Diet for a Guinea Pig (Oct 2025): about 2 tablespoons (1/8 cup) — https://www.vethope.cz/en/nutrition-of-guinea-pigs/ and https://www.pdsa.org.uk/pet-help-and-advice/looking-after-your-pet/small-pets/your-guinea-pig-s-diet and https://www.merckvetmanual.com/all-other-pets/guinea-pigs/diet-for-a-guinea-pig, read on 2026-09-19
• Fresh vegetables: PDSA, Your guinea pigs' diet (Oct 2024): one cup of fresh vegetables, greens and foraged foods per guinea pig daily (Guinea Lynx, Diet: about a cup a day). Grams from USDA FoodData Central, SR Legacy (2019): 1 cup shredded romaine = 47 g, 1 cup chopped red bell pepper = 149 g; midpoint 98 g used for a mixed cup — https://www.pdsa.org.uk/pet-help-and-advice/looking-after-your-pet/small-pets/your-guinea-pig-s-diet and https://www.guinealynx.info/diet.html and https://fdc.nal.usda.gov/food-details/169247/measures and https://fdc.nal.usda.gov/food-details/170108/measures, read on 2026-09-19
• Vitamin C: VCA Animal Hospitals, Guinea Pigs: Feeding (updated 14 Aug 2026): 10 mg to 50 mg of vitamin C a day, midpoint 30 mg (University of Florida Small Animal Hospital: 10-30 mg a day; Guinea Lynx, Diet: 10-30 mg per kg) — https://vcahospitals.com/know-your-pet/guinea-pigs-feeding and https://smallanimal.vethospital.ufl.edu/clinical-services/zoological-medicine/how-to-care-for-your-pet-guinea-pig and https://www.guinealynx.info/diet.html, read on 2026-09-19
• Pellet bag: Oxbow Animal Health, Essentials Adult Guinea Pig Food: sold in 5, 10 and 25 lb bags; 5 lb = 2.27 kg (retail size only) — https://oxbowanimalhealth.com/product/essentials-adult-guinea-pig-food/, read on 2026-09-19
• Hay bag: Oxbow Animal Health, Western Timothy Hay: sold in 15, 40 and 90 oz bags and 9, 25 and 50 lb boxes; 40 oz = 1.13 kg (retail size only) — https://oxbowanimalhealth.com/product/western-timothy/, read on 2026-09-19

UK and metric starting values have their own sources, shown under each field when you switch region.

Amounts are published averages for planning, not veterinary advice; a vet decides what an individual animal needs, and any sudden change in eating is a reason to see one.