Dog Medication Calculator
A free dog medication calculator that does the dosing maths by weight: enter your dog’s weight, the prescribed mg/kg rate and the strength on the label to get the dose in mg, tablets or mL. Plus common OTC dose ranges, a safe-dose checker, a unit converter and a list of human medicines that are dangerous for dogs.
How to Calculate a Dog’s Medication Dose
The tabs above cover the full job: the Dose Calculator for any prescribed mg/kg rate, OTC Meds for the dose ranges of common over-the-counter medicines vets sometimes suggest, a Safe-Dose Check to compare a planned dose against a safe maximum, a Unit Converter for lb/kg and mg/mL, and a Never Give list of human medicines that are dangerous — even deadly — for dogs.
The Veterinary Dosage Formula
Every weight-based dose comes down to three steps. Getting the units right is what keeps it safe:
2. Total dose: milligrams = weight (kg) × dose rate (mg/kg).
3. Amount to give: tablets = total mg ÷ mg per tablet; or mL = total mg ÷ mg per mL (1 mL = 1 cc).
Worked example: a 15 kg dog on a drug dosed at 5 mg/kg needs 15 × 5 = 75 mg per dose. If the liquid is 25 mg/mL, that is 75 ÷ 25 = 3 mL. If it comes as 25 mg tablets, that is 3 tablets. Double-check every figure, and never round up “to be safe” — with medication, more is not safer.
Common OTC Medications for Dogs
A few over-the-counter human medicines are sometimes recommended by vets for dogs. The ranges below are widely cited, but they are a starting point for a conversation with your vet, not a green light — dose, frequency and suitability depend on the individual dog.
| Medication | Typical range | Common use | Key caution |
|---|---|---|---|
| Diphenhydramine (Benadryl) | 2–4 mg/kg, 2–3× daily | Allergies, itching | Plain product only — never “-D” |
| Cetirizine (Zyrtec) | 0.5–1 mg/kg, once daily | Itching, allergies | Never Zyrtec-D (pseudoephedrine) |
| Loratadine (Claritin) | 0.25–0.5 mg/kg, once daily | Allergies | Never Claritin-D |
| Famotidine (Pepcid AC) | 0.5–1 mg/kg, 1–2× daily | Stomach acid, nausea | Give before food |
| Omeprazole (Prilosec) | 0.5–1 mg/kg, once daily | Ulcers, reflux | Give 30 min before food |
Human Medicines You Should Never Give a Dog
Some of the most common items in a medicine cabinet are among the most dangerous for dogs. Never give any of these without explicit veterinary direction:
| Medicine | Why it’s dangerous |
|---|---|
| Ibuprofen (Advil, Motrin) | Stomach ulcers and kidney failure, even at low doses. |
| Acetaminophen / Paracetamol (Tylenol) | Liver damage and red-blood-cell injury. Vet prescription only. |
| Naproxen (Aleve) | Extremely toxic — a single tablet can poison a dog. |
| Pseudoephedrine (Sudafed, “-D”) | Stimulant toxicity — dangerous heart rate and blood pressure. |
| Xylitol (sugar-free products) | Rapid blood-sugar crash and liver failure. |
Factors That Change the Right Dose
Weight is only the starting point. A safe dose also depends on the individual dog, which is why a calculator can never replace a vet. Kidney and liver function change how a drug is cleared; age matters because puppies and seniors process drugs differently; and other medications can interact dangerously. Some breeds carry the MDR1 gene mutation (common in collies, Australian shepherds and related herding breeds) that makes certain drugs — such as some anti-parasite and anti-diarrhoea medicines — dangerous at normal doses. Pregnant or nursing dogs, and dogs with heart or clotting problems, need special care. Always give your vet the full picture.
Frequently Asked Questions
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