Based on Veterinary Guidelines  ·  Privacy First  ·  Updated for 2026

Guinea Pig Feeding Calculator

Estimate how much hay, pellets, fresh vegetables, and water your guinea pig needs daily - based on weight, age, and group size.

Weight is not used in the amounts: the sources give amounts per guinea pig.
Results are estimates only and should not replace professional veterinary advice. Individual needs may vary.

How It Works

  • Based on age stage and group size
  • Provides hay, pellet, and vegetable guidance
  • Shows pellet and fresh food amounts from Merck and PDSA
  • Links to the Vitamin C Calculator

Free to use, no sign-up

Quick Answer

Merck says guinea pigs should eat roughly their body size in hay daily, about 1 to 2 teaspoons of pellets and 1 to 2 cups of fresh produce. PDSA gives hay and grass as 85 to 90% of the diet, one tablespoon of pellets and about one cup of fresh food in at least five to six types. The sources differ, so this calculator shows both and says to ask your veterinarian. It gives no water volume because no source we checked does.

The Basics

How This Tool Works

Enter the number of guinea pigs and the age stage to see published daily hay, pellet and fresh food figures.

  1. You provide how many guinea pigs you're feeding and their age stage.
  2. The calculator shows the Merck pellet and fresh food figures, scaled by how many guinea pigs you have, with PDSA figures in the notes. Hay is shown as unlimited.
  3. Growing guinea pigs get a note to ask your veterinarian, because no source we checked gives amounts for babies.
Nutrition Basics

What the Sources Say About Guinea Pig Diets

Figures from the Merck Veterinary Manual, PDSA, VCA Animal Hospitals and the RSPCA. Where they differ, we say so.

Hay

Merck: roughly the guinea pig's body size in hay daily. PDSA: hay and grass are 85 to 90% of the diet. VCA: unlimited low-calcium hay. Merck says growing, pregnant and lactating guinea pigs need alfalfa hay and pellets.

Pellets

Merck: about 1 to 2 teaspoons of guinea pig pellets a day. PDSA: one tablespoon per adult a day. RSPCA: a fresh portion daily, because vitamin C in pellets breaks down over time. Ask your veterinarian which suits your guinea pig.

Fresh food

Merck: 1 to 2 cups of fresh produce a day, focusing on vegetables high in vitamin C. PDSA: about one cup a day, at least five to six types. Iceberg lettuce is advised against by VCA, RSPCA and PDSA.

Water

Merck says intake is higher from a bottle than a bowl, and that sipper tubes get dirty, so check water and nozzles often. No source we checked gives a daily volume per kg.

Vitamin C

Guinea Pigs & Vitamin C

PDSA and RSPCA say guinea pigs need vitamin C from their diet because they cannot produce it themselves. Merck says adults typically need 10 to 25 mg per kg a day, and 30 mg per kg or more when growing, pregnant, nursing or ill. Merck names bell peppers, kale, parsley and spinach as high in vitamin C, and VCA names bell pepper, tomato, turnip, collard greens, asparagus, orange and kiwi. Merck and PDSA advise against adding vitamin C to drinking water. Use our Guinea Pig Vitamin C Calculator, and contact a licensed veterinarian if you have any concern about your guinea pig's health.

Methodology

How Results Are Estimated

Guinea pig feeding guidance is given as fixed amounts per animal, not a calorie formula. The figures come from named sources, and where they differ the tool says so.

Merck says growing (under 6 months), pregnant and lactating guinea pigs require alfalfa hay and pellets. We found no source with amounts for babies, so the tool says to ask your veterinarian. Weight is not used, because the sources give amounts per guinea pig.

Hay: unlimited (Merck: roughly body size daily; PDSA: 85-90% of the diet) Pellets per guinea pig: 1-2 teaspoons (Merck); PDSA gives 1 tablespoon Fresh produce per guinea pig: 1-2 cups (Merck); PDSA gives about 1 cup in 5-6 types Water: fresh at all times; no daily volume is published Totals scale with however many guinea pigs you are feeding.

Important Limitations

This tool provides an estimate, not a diagnosis. Keep these limitations in mind when reading your result:

  • These are published per-animal figures, not tailored to an individual guinea pig's health or activity.
  • Merck and PDSA differ on pellet amounts (1-2 teaspoons versus one tablespoon), so ask your veterinarian.
  • Guinea pigs cannot make their own vitamin C (PDSA, RSPCA), so vegetable variety matters; this tool does not check nutrient completeness. See our Vitamin C Calculator.
  • This tool does not diagnose any condition. If your guinea pig stops eating or its droppings change, contact a licensed veterinarian promptly.
  • Results are educational estimates only. Contact a licensed veterinarian for your guinea pig's feeding plan.
Worked Example

Example Calculation

How the daily diet is shown for two adult guinea pigs.

  1. Pellets (Merck): 2 guinea pigs × 1-2 teaspoons = 2-4 teaspoons per day. PDSA gives one tablespoon per adult.
  2. Fresh produce (Merck): 2 guinea pigs × 1-2 cups = 2-4 cups per day. PDSA gives about one cup each.
  3. Water: fresh at all times.
  4. Hay: unlimited grass hay, available at all times.
Estimated result: for two adult guinea pigs, 2-4 teaspoons of pellets (Merck) and 2-4 cups of fresh produce (Merck), with unlimited hay and fresh water. Ask your veterinarian.
FAQs

Frequently Asked Questions

Merck says guinea pigs should eat roughly their body size in hay daily, about 1 to 2 teaspoons of guinea pig pellets and 1 to 2 cups of fresh produce. PDSA gives hay and grass as 85 to 90% of the diet, one tablespoon of pellets and about one cup of fresh food in at least five to six types. The figures differ, so ask your veterinarian what suits your guinea pig.

VCA advises unlimited low-calcium hay, and Merck recommends high-quality grass-based hay for adults. Merck says growing (under 6 months), pregnant and lactating guinea pigs require alfalfa hay and pellets.

The sources differ. Merck gives approximately 1 to 2 teaspoons of pellets a day and PDSA gives one tablespoon per adult a day. RSPCA says to give a fresh portion daily rather than topping up the bowl, because vitamin C in pellets breaks down over time. Ask your veterinarian.

Merck recommends 1 to 2 cups of fresh produce a day, and PDSA recommends about one cup a day in at least five to six types. RSPCA lists parsley, celery, bell peppers, cucumber and romaine as foods guinea pigs can eat often, and broccoli, spinach, kale and carrot as treats a few times a week. See our Can Guinea Pigs Eat This? tool.

Provide fresh water at all times. Merck says intake is higher from a bottle than from a bowl, and that sipper tubes get dirty, so water and nozzles need frequent checks. We found no source that gives a daily volume, so this tool does not give one. Contact a licensed veterinarian if your guinea pig's drinking changes.

PDSA and RSPCA say guinea pigs need vitamin C from their diet because they cannot produce it. Merck says adults typically need 10 to 25 mg per kg a day, and 30 mg per kg or more when growing, pregnant, nursing or ill. See our Guinea Pig Vitamin C Calculator, and ask your veterinarian.

The sources advise only occasional, small amounts. VCA says to offer fruit only occasionally and in small amounts because excess sugar can disrupt intestinal bacteria. PDSA says fruit only in very small amounts because it is high in sugar. Merck says other fruits (including berries and oranges), carrots and sugary treats should not be fed.

PDSA lists potatoes and their skin, onion, garlic, mushrooms, tomato vine and leaves, avocado, iceberg lettuce, rhubarb and its leaves, and chives as unsafe. VCA says not to feed oats, seeds, nuts or dry cereals. See our Can Guinea Pigs Eat This? tool.

Yes. This calculator shows published figures and cannot account for your guinea pig's health or condition. If your guinea pig stops eating or its droppings change, contact a licensed veterinarian promptly.
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References

General public resources referenced while researching this tool's topic.

Editorial Note

This tool is part of PetNurture's educational library. Its formulas and guidance draw on publicly available educational resources, recognised veterinary organisations, and established animal welfare references where appropriate — see the References section below for the specific sources used on this page.

It is provided for general educational purposes and is not a substitute for advice, diagnosis, or treatment from a qualified veterinarian.

Educational Use Notice

Last updated: May 2026

The information provided by this tool is for general educational and informational purposes only. Results are estimates, not a diagnosis, and may vary based on your pet's breed, age, health conditions, activity level, diet, and individual factors.

PetNurture does not provide veterinary, medical, or emergency care advice. Always consult a licensed veterinarian or qualified pet care professional regarding your pet's specific health, nutrition, or medical needs.

While we strive to keep calculations accurate and up to date, PetNurture makes no guarantees regarding completeness, reliability, or accuracy. Use this tool at your own discretion.

How we calculate results: This tool uses commonly referenced veterinary formulas, feeding guidelines, and breed-size estimates to provide general educational guidance. Individual pets may have different nutritional, behavioral, or medical needs that are not captured by any generalized formula.

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AI Overview & Key Facts

  • Purpose: Instant educational estimates to assist pet owners in tracking primary physiological metrics.
  • Input Parameters: Number of guinea pigs, weight, and age group.
  • Reference Guidelines: Ratios are informed by general public guidance from sources such as the AEMV and RSPCA.
  • Liability Limitation: Educational estimation only, not a diagnosis. Consult a licensed veterinarian for clinical assessments.

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