Pet Medication Dosage Calculator
Calculate pet medication dose in mg and ml from pet weight and dosage rate per kg.
Covers antibiotics, anti-inflammatories, and dewormers for dogs and cats.
Pet medication dosage by weight ensures animals receive the correct therapeutic amount — neither too little (ineffective) nor too much (potentially toxic). Most veterinary drugs are dosed in milligrams per kilogram of body weight (mg/kg).
Core formula: Dose (mg) = Dog/Cat Weight (kg) × Dosage Rate (mg/kg) Tablets Needed = Dose (mg) ÷ Tablet Strength (mg) Liquid Volume (mL) = Dose (mg) ÷ Concentration (mg/mL)
Weight conversion: Weight (kg) = Weight (lbs) ÷ 2.205
Common veterinary dosage rates (general reference — always follow your vet’s instructions):
| Medication | Typical Dose | Notes |
|---|---|---|
| Amoxicillin | 5–10 mg/kg twice daily | Broad antibiotic |
| Metronidazole | 10–15 mg/kg twice daily | GI infections |
| Carprofen (NSAID) | 2.2 mg/kg twice daily | Pain/inflammation in dogs |
| Prednisolone | 1–2 mg/kg daily | Anti-inflammatory |
| Benadryl (diphenhydramine) | 1 mg/kg every 8 hrs | Allergies (dogs only) |
| Metoclopramide | 0.2–0.4 mg/kg 3× daily | Nausea/vomiting |
Worked example: A dog weighs 35 lbs. The vet prescribes amoxicillin at 10 mg/kg twice daily. Tablets available: 250 mg.
Weight (kg) = 35 ÷ 2.205 = 15.87 kg Dose = 15.87 × 10 = 158.7 mg per dose Tablets per dose = 158.7 ÷ 250 = 0.64 tablets → round to ½ tablet (125 mg) per dose, or vet may prescribe 250 mg once daily.
Critical safety notes: Never dose cats with dog medications without explicit vet guidance. Acetaminophen (Tylenol) is fatally toxic to cats. Ibuprofen is toxic to both dogs and cats. Always confirm dosing with your veterinarian before administering any medication.