Determine the ideal diet portions for small mammals. Calculate hay, pellet, and vegetable amounts for rabbits, guinea pigs, and hamsters.
Calculate daily food requirements for rabbits, guinea pigs, and hamsters.
Provide the perfect diet for your pocket pet with the Small Mammal Nutrition Calculator. Rabbits, guinea pigs, and hamsters have highly specialized digestive systems that differ significantly from dogs and cats. Just as humans benefit from tracking their macronutrient intake, these small herbivores and omnivores require a precise balance of fiber, fresh vegetables, and limited pellets.
The foundation of rabbit and guinea pig health is unlimited Timothy hay, which provides essential fiber for gut motility and wears down their continuously growing teeth. Without adequate fiber, these animals can develop life-threatening conditions like GI stasis. Hamsters, as omnivores, have different needs—requiring a balanced mix of grains, seeds, and occasional protein.
One critical difference: guinea pigs cannot synthesize their own Vitamin C (just like humans!), making them susceptible to scurvy. They require 10-30mg of Vitamin C daily from fortified pellets and fresh vegetables like bell peppers and parsley.
| Species | Primary Diet | Hay Requirement | Special Notes |
|---|---|---|---|
| Rabbit | Herbivore | 80% of diet | Limit pellets; avoid high-sugar treats |
| Guinea Pig | Herbivore | 80% of diet | Requires Vitamin C supplementation |
| Hamster | Omnivore | Bedding only | Needs protein; can eat insects |
For a 5 lb rabbit: Provide unlimited Timothy hay (should eat a body-sized pile daily), 1/4 cup plain pellets, 1.25 cups mixed leafy greens (romaine, cilantro, parsley), and fresh water. Limit fruit to 1-2 tablespoons as occasional treats.
| Species | Weight | Pellets | Fresh Veggies |
|---|---|---|---|
| Adult Rabbit (4 lbs) | 1.8 kg | 1/4 cup | 1 cup leafy greens |
| Large Rabbit (10 lbs) | 4.5 kg | 1/2 cup | 2.5 cups leafy greens |
| Guinea Pig (2 lbs) | 0.9 kg | 1/8 cup | 1 cup + Vitamin C source |
| Syrian Hamster | 120-150g | 1-2 tbsp mix | Tiny pieces (treats only) |
All species require unlimited Timothy hay except hamsters.
| Nutrient | Rabbit | Guinea Pig | Hamster |
|---|---|---|---|
| Fiber requirement | 18-25% | 15-20% | 6-15% |
| Protein | 12-14% | 14-16% | 15-18% |
| Fat | 2-4% | 3-4% | 4-7% |
| Vitamin C (daily) | Synthesizes own | 10-30 mg | Synthesizes own |
Related tools: Pet Meal Calculator for dogs and cats, Exotic Pet Nutrition for ferrets and hedgehogs, and Bird Nutrition Calculator for feathered friends.
Daily food amounts for small mammals are calculated based on body weight and species-specific nutritional needs. Rabbits: Unlimited Timothy or orchard grass hay (80% of diet) + 1/4 cup high-fiber pellets (18%+ fiber) per 5 lbs of body weight + 1 cup of fresh leafy greens per 4 lbs of body weight. Avoid sugary fruits and iceberg lettuce. Guinea pigs: Unlimited hay + 1/8 cup plain pellets (fortified with Vitamin C) + 1 cup of fresh vegetables per day. Bell peppers, romaine lettuce, and cilantro are excellent vitamin C sources. Hamsters: 1–2 teaspoons of a balanced hamster mix daily (seeds, grains, and pellets) + occasional fresh vegetables (no citrus). All three species benefit from constant access to fresh, clean water. Overfeeding pellets is a common mistake—hay should always be the primary food source for rabbits and guinea pigs to maintain proper gut motility and dental wear.
Rabbits should have unlimited access to hay at all times—it should comprise approximately 80% of their total diet. The recommended volume is a hay bundle roughly equal to the rabbit's own body size per day. Timothy hay is the gold standard for adult rabbits (over 7 months old) due to its ideal calcium-to-phosphorus ratio and high fiber content. Orchard grass and meadow hay are good alternatives. Alfalfa hay is too high in calcium and protein for adult rabbits and should only be fed to young rabbits under 7 months or pregnant/nursing does. Hay is critically important for two reasons: (1) The long fiber strands are essential for maintaining healthy gut motility—without adequate hay, rabbits can develop life-threatening GI stasis. (2) Rabbits' teeth grow continuously throughout their lives, and chewing tough hay fibers naturally wears them down, preventing painful dental overgrowth (malocclusion).
Yes, absolutely. Guinea pigs are one of very few mammals—along with humans and non-human primates—that lack the enzyme L-gulonolactone oxidase, which is required to synthesize Vitamin C internally. This means they must obtain all their Vitamin C from their diet. Guinea pigs require 10–30 mg of Vitamin C per day for maintenance, and up to 50 mg per day for pregnant or sick animals. Deficiency causes scurvy within 2–4 weeks, with symptoms including rough coat, swollen joints, lethargy, reluctance to move, weight loss, and dental problems. The best dietary sources include fresh bell peppers (1/4 red bell pepper provides ~35mg of Vitamin C), fresh parsley, kale, broccoli, and romaine lettuce. Avoid relying solely on pellets for Vitamin C as it degrades rapidly with heat, light, and age—pellets lose most of their Vitamin C within 90 days of manufacture. Vitamin C drops added to water also degrade quickly and create a bitter taste that discourages drinking.