Important: This calculator is for veterinary professional reference only. Always verify dosages against current formulary references and adjust for individual patient factors. Do not use for self-prescribing.
Select species, enter weight, and choose a medication, then click calculate.
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What This Calculator Does
This pet medication dosage calculator helps veterinarians, veterinary technicians, and veterinary students quickly calculate weight-based drug dosages for dogs and cats. It includes 12 of the most commonly prescribed veterinary medications with dose ranges, frequencies, and clinical notes sourced from the 2026 edition of Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual. Select a species, enter the patient's weight in kilograms or pounds, choose a medication, and get the per-dose and daily dose ranges instantly.
The Formula
The dose for most veterinary medications is calculated by multiplying the patient's body weight in kilograms by the prescribed dose rate in mg/kg. If the weight is given in pounds, it is first converted to kilograms by dividing by 2.2 (or multiplying by 0.4536). The daily dose depends on the dosing frequency: a drug given every 12 hours (BID) is administered twice daily, while every 8 hours (TID) means three times daily. The calculator accounts for species-specific dose ranges, as some drugs have different recommendations for dogs versus cats.
Step-by-Step Example
Select species
Choose dog or cat. The drug list filters to show only medications appropriate for the selected species.
Enter body weight
Enter the patient weight. Example: 25 kg dog. If using pounds, toggle to lbs and the calculator converts automatically.
Choose medication
Select amoxicillin (10-25 mg/kg). The calculator shows the dose range and frequency.
Read the result
Per-dose range: 250 to 625 mg. Frequency: every 8-12 hours. Daily dose: 625 to 1,562 mg. Round to the nearest practical tablet size.
Real-World Use Cases
Emergency and After-Hours Dosing
Quickly verify dosages during urgent care situations when formulary references may not be immediately at hand.
Client Communication
Show pet owners the exact dosage calculation to explain why their pet needs a specific number of tablets or volume of liquid medication.
Veterinary Student Training
Practice weight-based dose calculations and learn standard dose ranges for commonly prescribed drugs across species.
Common Mistakes to Avoid
Not converting pounds to kilograms before calculating. A 25 lb dog is 11.3 kg, not 25 kg. Using the wrong unit doubles the dose and can cause toxicity.
Applying dog dose ranges to cats without checking. Some drugs have different dose ranges or are contraindicated in cats. Enrofloxacin in cats must not exceed 5 mg/kg/day due to retinal toxicity risk.
Forgetting to adjust for organ dysfunction. Patients with hepatic or renal compromise may need reduced doses or longer intervals. Standard dose ranges assume normal organ function.
Not rounding to practical dosing units. A calculated dose of 187 mg needs to be rounded to available tablet sizes (e.g., 200 mg tablet or a measurable liquid volume).
Using NSAIDs and corticosteroids concurrently. Carprofen or meloxicam should never be given with prednisone or dexamethasone due to severe GI ulceration risk.
Frequently Asked Questions
Accuracy and Disclaimer
This calculator is for licensed veterinary professional reference only. Dosages are based on standard formulary ranges and must be verified against current references. Individual patient factors including species, breed, age, weight, organ function, and concurrent medications must be considered. Do not use this tool for self-prescribing or treating animals without veterinary supervision.
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