One of the most critical aspects of snake husbandry is offering the correct size prey. Feed too small, and your snake will be malnourished. Feed too large, and you risk severe regurgitation or internal injury.
So, what size mouse or rat for a Ball Python? This guide removes the guesswork using the two golden rules of reptile feeding (for a complete schedule, see our Ball Python feeding guide).
1. The Two Golden Rules of Sizing
Veterinarians and breeders use two foolproof methods to determine prey size:
Rule #1: The Girth Rule
The prey item should be exactly the same size, or slightly larger (up to 1.25x), than the thickest part of your snake's midsection. If you look at the mouse and it looks substantially wider than the fattest part of your snake's belly, it is too big.
Rule #2: The Weight Rule (The Best Method)
Invest in a cheap digital kitchen scale. Weighing your snake in grams allows for mathematical precision. The prey item should weigh between 10% and 15% of the snake's total body weight.
Example: If your Ball Python weighs 500 grams, you should feed it a rat that weighs between 50g and 75g (which equates to a Weaned Rat).
2. Ball Python Size and Weight Chart
Use this quick reference chart to match your Ball Python's weight to the appropriate feeder from Loxahatchee Rodents (refer to our frozen rat size chart for exact dimensions).
| Snake Weight (g) | Age/Life Stage | Appropriate Prey (10-15% of body weight) |
|---|---|---|
| 50g - 100g | Hatchling | Rat Pinky (5-10g) OR Hopper Mouse |
| 100g - 250g | Young Juvenile | Rat Fuzzy (10-20g) OR Adult Mouse |
| 250g - 500g | Juvenile | Rat Pup (20-30g) OR Jumbo Mouse |
| 500g - 800g | Sub-Adult | Weaned Rat (30-50g) |
| 800g - 1500g | Adult Male | Small Rat (50-90g) |
| 1500g - 2500g+ | Large Adult Female | Medium Rat (90-150g) |
3. Should I Feed Mice or Rats?
While Ball Pythons will happily eat mice, it is highly recommended to switch them to rats as early as possible.
Adult Ball Pythons require prey that weighs 80g to 150g. An adult mouse only weighs about 25g to 30g. If you only feed mice, you would have to feed an adult Ball Python 3 to 5 mice per feeding to meet its caloric needs. This is hard on their digestive system. A single appropriately sized rat is far more nutritious and easier to digest.
Conclusion
Always rely on a digital scale to dictate your feeding choices. By sticking to the 10-15% weight rule, you guarantee your Ball Python is receiving exactly what it needs to grow strong (and don't forget to check how often to feed your snake based on its age) without risking the deadly complications of overfeeding or underfeeding.