About feeding a pet rat
Pet rats are intelligent omnivores and, sadly, prone to obesity and diet-linked tumours — so a balanced, not-too-rich diet genuinely affects both their quality and length of life. Fresh food and portion control matter more than most owners realise.
How much should a pet rat eat?
Calorie needs use the veterinary formula 70 × weight(kg)0.75 (the Resting Energy Requirement), multiplied by a lifestyle factor of ×1.8 for a typical pet rat at the life stage shown. Enter your own animal's details in the calculator for an exact figure.
| Body weight | Daily calories |
|---|---|
| 200 g | 38 kcal |
| 257 g | 45 kcal |
| 314 g | 53 kcal |
| 371 g | 60 kcal |
| 429 g | 67 kcal |
| 486 g | 73 kcal |
| 543 g | 80 kcal |
| 600 g | 86 kcal |
What to feed
A good rat diet is a formulated rat block or a balanced homemade grain mix as the base, plus fresh vegetables and small amounts of fruit and protein. Avoid high-fat, high-sugar human snacks and seed-heavy mixes that rats will over-select.
How often to feed
Offer measured food once or twice a day; many keepers scatter-feed to encourage foraging. Rats will hoard and over-eat rich treats, so treats should be small and occasional.
Common feeding mistakes
- Sugary, fatty human foods and treats.
- Seed-and-nut mixes that rats selectively over-eat.
- Free-feeding calorie-dense food leading to obesity.
- Too much protein for older rats, which can stress kidneys.
Weight & health
Obesity and mammary/other tumours are common in pet rats. A balanced, moderate diet, plenty of climbing exercise, and limited rich treats support a longer, healthier life.
Frequently asked questions
What should I feed a pet rat?
A formulated rat block or balanced grain mix as the base, plus fresh vegetables, a little fruit, and small amounts of protein. Keep fatty, sugary treats occasional.
How much do rats eat per day?
Adult rats eat roughly 15-30 g of food a day depending on size and activity. Offer measured meals and adjust to keep a lean, healthy body condition.
Can rats eat fruit and vegetables?
Yes — many vegetables and small amounts of fruit are healthy additions. Avoid a few toxic items (like green potato and citrus for males) and keep sugary fruit modest.
Why do pet rats get tumours?
Rats are genetically prone to tumours, but diet and body condition play a role — obesity increases risk. A balanced diet and exercise help, though genetics remain a major factor.