What this calculator does
This tool estimates the fenbendazole (commonly sold as Panacur) deworming dose for a dog based on its body weight. The widely cited canine rate is 50 mg per kilogram of body weight, given once daily for 3 to 5 consecutive days. Enter your dog's weight in kilograms or pounds and the calculator returns the daily milligram dose plus the total dose across the whole treatment course. This information is educational only — dosing, product choice and treatment length should always be confirmed by your veterinarian.
How to use it
Weigh your dog as accurately as you can. Choose kilograms or pounds (pounds are converted using \(1\text{ lb} = 0.4536\text{ kg}\)). Leave the dose rate at the default 50 mg/kg unless your vet has specified a different rate, then set the number of treatment days (commonly 3 for routine worming, up to 5 for Giardia). The result shows the mg of active fenbendazole needed each day and for the full course.
The formula explained
The daily dose is simply the dose rate multiplied by weight: $$\text{Daily dose (mg)} = 50\text{ mg/kg} \times \text{weight (kg)}$$ The total course dose multiplies that by the number of days. Note this gives milligrams of active fenbendazole, not millilitres of a particular suspension or grams of a paste — concentration varies by product, so always read the label.
Worked example
A 10 kg dog at 50 mg/kg needs $$50 \times 10 = 500\text{ mg per day}$$ Over a 3-day course that is $$500 \times 3 = 1{,}500\text{ mg total}$$ A 22 lb dog converts to about 9.98 kg, giving roughly 499 mg/day.
FAQ
Is 50 mg/kg correct for all dogs? It is the common reference rate, but puppies, pregnant dogs and specific parasites may need different protocols — ask your vet.
How do I convert mg to mL or grams? Divide the mg by the product's concentration (e.g. a 100 mg/mL suspension means \(500\text{ mg} = 5\text{ mL}\)). Check your product label.
Can I give the whole course in one dose? No. Fenbendazole is given once daily across consecutive days for full effect; do not combine days into one dose.
