Pet Medication Dosage Calculator - Online mg/kg Tool

mg/kg stands for milligrams of medication per kilogram of body weight. It's the standard way veterinarians calculate drug doses for animals. For example, if a drug is prescribed at 5 mg/kg and your dog weighs 10 kg, the total dose would be 5 × 10 = 50 mg. This weight-based approach ensures each pet receives a safe and effective amount tailored to their body size.

To convert pounds to kilograms, divide the weight in pounds by 2.205 (or multiply by 0.454). For example, a 22 lb dog weighs approximately 10 kg. Our calculator handles this conversion automatically — simply select "lb" as your weight unit, enter the value, and the tool converts it internally for accurate mg/kg dosing. You can also toggle between kg and lb, and the value will be converted automatically.

For liquid medications, the concentration tells you how many milligrams of active ingredient are in each milliliter (mL) of liquid. Common concentrations include 50 mg/mL, 100 mg/mL, or 250 mg/mL. Without knowing the concentration, you cannot accurately measure the correct volume to administer. For example, if your pet needs 50 mg of a drug and the concentration is 100 mg/mL, you would give 0.5 mL. For tablets or capsules, concentration is not needed — you simply give the appropriate fraction of a tablet based on the total mg dose.

This calculator is designed for dogs, cats, and common companion animals. However, it should only be used with a veterinarian's prescribed dosage. Different species metabolize drugs differently — a safe dose for a dog may be toxic for a cat. Never self-prescribe medications. Always consult your veterinarian for the correct mg/kg dosage specific to your pet's condition, species, breed, age, and health status. This tool helps you compute the dose — the prescription must come from a professional.

For volumes under 1 mL, use a 1 mL syringe (often called an insulin or tuberculin syringe) with clear 0.01 mL markings. For volumes between 1-5 mL, a 3 mL or 5 mL oral dosing syringe works well. Never use household spoons — they are highly inaccurate. Always draw liquid to the correct line at eye level, and ensure no air bubbles are present. If the calculated volume seems impractical (e.g., 0.02 mL), consult your vet — the medication may need to be diluted or a different formulation used.

If you miss a dose, give it as soon as you remember — unless it's almost time for the next scheduled dose. In that case, skip the missed dose and continue with the regular schedule. Never double-dose to "catch up," as this can lead to overdose and serious side effects. Always check the medication's package insert or call your veterinarian for specific guidance, as recommendations vary by drug.

Not all tablets can be cut or crushed. Extended-release (XR/ER), enteric-coated, and certain encapsulated medications must be given whole. Cutting them can release the entire dose at once, causing toxicity. Always check the label or ask your pharmacist/veterinarian. If cutting is safe, use a pill splitter for accuracy — manual splitting with a knife can result in uneven pieces and incorrect dosing.