Pet Medication Dosage Calculator
This calculator converts a prescribed dose rate (mg/kg) into the volume (mL) of liquid medication to administer. Enter your pet's body weight, the dose rate your veterinarian has prescribed, and the concentration of the liquid medication. The calculator returns the total dose in milligrams and the volume to draw up or administer. Always confirm every dose with a licensed veterinarian before giving any medication to your pet. This tool is for cross-checking and educational use only.
Veterinary dosage formula
Total dose (mg) = body weight (kg) x dose rate (mg/kg)
Volume (mL) = total dose (mg) / concentration (mg/mL)
This is the standard weight-based dosing approach used in veterinary pharmacology and described in Plumb's Veterinary Drug Handbook. The dose rate (mg/kg) is species-specific and condition-specific; it must be confirmed by a licensed veterinarian for each patient and drug.
Important safety notes
- Always obtain the dose rate from a licensed veterinarian, not from internet sources.
- Double-check the concentration on the medication label before calculating.
- Some drugs have narrow therapeutic windows; a small error in dose can cause harm.
- Many human medications (paracetamol, ibuprofen, xylitol) are toxic to dogs and cats even at low doses.
- Confirm frequency (once daily, twice daily, etc.) and route (oral, injectable) with your vet.
Pet medication dosage calculator: frequently asked questions
How is pet medication dosage calculated?
The standard veterinary pharmacology formula is: Total dose (mg) = body weight (kg) x prescribed dose rate (mg/kg). Volume to administer (mL) = total dose (mg) / drug concentration (mg/mL). Always confirm the prescribed dose rate with your veterinarian.
What does mg/kg mean in veterinary dosing?
mg/kg means milligrams of drug per kilogram of body weight. If a drug is prescribed at 5 mg/kg and the pet weighs 10 kg, the total dose is 50 mg.
What is drug concentration and where do I find it?
Drug concentration is the amount of active ingredient per unit volume of solution, typically expressed as mg/mL. It appears on the medication label or package insert. For example, amoxicillin oral suspension 50 mg/mL means each 1 mL contains 50 mg.
Can I use this for cats and dogs?
Yes. The weight-based dosing formula applies to both species. However, cats have different metabolic pathways for many drugs. Always use a dose rate specifically confirmed for the target species by your veterinarian.
Is this calculator a substitute for veterinary advice?
No. This tool is for educational and cross-checking purposes only. Never administer medication to a pet without first confirming the dose, route, and frequency with a licensed veterinarian. Some human medications are toxic to animals even at low doses.
Official sources
- Plumb, D.C.: Plumb's Veterinary Drug Handbook (standard veterinary pharmacology reference).
- AVMA: Medications and Your Pet.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.