Pet Medication Dosage Calculator
Free pet medicine dose calculator: converts a weight-based mg per kg dose into the millilitres to draw, for common vet-prescribed drugs.
What does the Pet Medication Dosage Calculator do?
It turns a standard weight-based dose in milligrams per kilogram into the milligrams, and then the millilitres to draw, for a few medicines veterinarians commonly prescribe.
- Inputs: pet weight in kilograms and the medication.
- Output: dose in milligrams and the volume in millilitres.
- Method: weight times the standard mg per kg rate, divided by the liquid concentration.
Quick answer
A 10 kg pet on metronidazole at 10 mg per kg needs 100 mg, which is 2 mL of the 50 mg per mL liquid. This is a reference figure only: your veterinarian sets the real dose, frequency and any adjustment.
What This Calculator Really Does
Veterinary doses are almost always written as milligrams of drug per kilogram of body weight. Liquid medicines, however, are measured in millilitres on the syringe. Converting between the two is where pet owners most often make an error, because the concentration of the liquid matters as much as the dose. This calculator does the two-step conversion: first multiply the weight by the mg per kg rate to get the dose in milligrams, then divide by the concentration in mg per mL to get the volume to draw. It covers a few common medications so the arithmetic is transparent.
The rules it applies
- Dose in mg: body weight in kg multiplied by the standard mg per kg rate for that drug.
- Volume in mL: the dose in milligrams divided by the concentration in mg per mL.
- Included drugs: meloxicam, metronidazole, amoxicillin and gabapentin, at typical liquid concentrations.
- Not modelled: frequency, duration, loading doses, and any reduction for kidney or liver disease, all of which a vet decides per animal.
Worked example with real numbers
A 10 kg pet prescribed metronidazole at 10 mg per kg. The dose is 10 x 10 = 100 mg. The liquid is 50 mg per mL, so the volume is 100 / 50 = 2 mL. Change the pet to 25 kg and the same drug needs 250 mg, which is 5 mL. Change to meloxicam at only 0.1 mg per kg and the same 10 kg pet needs just 1 mg, a tiny fraction of a millilitre if the liquid is 1.5 mg per mL.
Reading the result
This is a reference aid, never a prescription. Several human medicines are highly toxic to pets — paracetamol and ibuprofen among them — and even a correct drug can be wrong at the wrong dose. Always confirm the drug, the dose, the frequency and the duration with your veterinarian, and use the measuring syringe that came with the medicine rather than a kitchen spoon. If your pet is vomiting, drowsy or unwell after a dose you believe was correct, contact your vet or an emergency animal hospital immediately.
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Frequently Asked Questions
How is the pet medication dose calculated?
Body weight in kilograms multiplied by the drug standard mg per kg rate gives the dose in milligrams, which is divided by the liquid concentration in mg per mL to give the millilitres to draw. The steps panel shows each figure.
What do I need to use the Pet Medication Dosage Calculator?
Your pet weight in kilograms and the medication name. The standard mg per kg rates and liquid concentrations are built in.
What does the result from the Pet Medication Dosage Calculator show?
The dose in milligrams and the equivalent volume in millilitres, so you can measure the syringe correctly.
Is this pet dosage calculator safe to use instead of a vet?
No. It is a reference aid only. Your veterinarian sets the real dose, frequency and duration, and several human medicines are toxic to pets. Never give medicine to a pet without veterinary instruction.
Is the Pet Medication Dosage Calculator really free?
Yes — 100 percent free, no sign-up, and everything runs in your browser.
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