What this calculator does
This tool estimates how much Imodium (the brand name for loperamide) might be given to a dog based on its body weight. A commonly cited canine dosing guideline is 0.1 mg per kilogram of body weight, given every 8 to 12 hours. Enter your dog's weight in kilograms or pounds and the calculator returns the per-dose amount in milligrams.
How to use it
Select your dog's weight unit, type in the weight, and leave the dose rate at the default 0.1 mg/kg (some veterinary references use up to 0.2 mg/kg). The result shows the milligrams per dose plus the converted weight and dose rate so you can double-check the math.
The formula explained
The calculation is simply $$\text{Dose (mg)} = \text{Dose (mg/kg)} \times \text{Weight (kg)}$$ If you enter pounds, the calculator first converts to kilograms by multiplying by \(0.453592\). Standard Imodium tablets are 2 mg and the liquid is 1 mg/mL, so you may need a partial tablet or measured liquid — another reason to confirm with your vet.
Worked example
A 20 kg dog at 0.1 mg/kg needs $$20 \times 0.1 = 2 \text{ mg per dose}$$ conveniently one 2 mg tablet, every 8–12 hours. A 10 lb dog converts to 4.54 kg, giving about 0.45 mg per dose.
FAQ
Is Imodium safe for all dogs? No. Herding breeds (Collies, Australian Shepherds, and others) often carry the MDR1 gene mutation that makes loperamide neurotoxic. Never use it in these breeds without veterinary guidance.
How often can I give it? The typical interval is every 8 to 12 hours, but only for a short course and only if your vet approves.
When should I avoid it entirely? Avoid loperamide if diarrhea may be caused by ingested toxins or bacterial infection, or if your dog is very young, pregnant, or has other health conditions. Always call your veterinarian first.
