VetDosing

Veterinary Dosage Calculator

Free dose-by-weight calculators for 556 veterinary drugs – for dogs, cats, horses, cattle and more. Every dose comes from the Saunders Handbook of Veterinary Drugs.

556 drug calculatorsDogs · Cats · Horses · Cattle · Sheep · Goats · PigsWeight in kg or lbFree, no sign-up

A46 calculators

B17 calculators

C65 calculators

D52 calculators

E20 calculators

F24 calculators

G15 calculators

H12 calculators

I22 calculators

K6 calculators

L20 calculators

M56 calculators

N15 calculators

O16 calculators

P62 calculators

Q2 calculators

R10 calculators

S27 calculators

T47 calculators

U2 calculators

V11 calculators

W1 calculators

X1 calculators

Y1 calculators

Z6 calculators

What Is a Veterinary Dosage Calculator?

A veterinary dosage calculator helps veterinarians, veterinary technicians and pet owners work out the dose of a medicine for an animal from its body weight, species and the route of administration. Choose the drug, select the species, enter the weight in kg or lb and pick the route: the calculator multiplies the weight by the dose rate listed in the handbook and shows the total dose and how often to give it.

Accurate dosing matters in veterinary medicine because animals differ so much in size and in how they handle drugs. A correct calculation helps prevent both under-dosing and overdosing.

How Does the Veterinary Dosage Calculator Work?

Most doses are given per kilogram of body weight, so the calculator uses this formula:

Total dose (mg) = Body weight (kg) × Dose rate (mg/kg)
  1. Find the drug in the A–Z list or with the search box above.
  2. Enter the body weight in kg or lb – pounds are converted automatically.
  3. Choose the species and route (for example PO, IV, IM or SQ).
  4. Read the result: total dose, dose rate, route and frequency, with the handbook page it comes from.

Examples: Ampicillin for a 10 kg dog at 20 mg/kg PO: 10 × 20 = 200 mg. Metronidazole for a 5 kg cat at 15 mg/kg PO: 5 × 15 = 75 mg.

Some drugs, mostly anticancer drugs, are dosed per square metre of body surface area (mg/m²) or as a fixed amount per animal; their calculators handle this automatically.

Common Dosage Rates

Examples from the calculators on this site (Saunders Handbook of Veterinary Drugs). Open a drug for all species and routes.

MedicationSpeciesRouteDose rate (mg/kg)Frequency10 kg animal
AmpicillinDogPO20-40q8h200-400 mg
AmpicillinCatIV, IM, SQ10-20q6-8h100-200 mg
MetronidazoleCatPO10-25q24h100-250 mg
CarprofenDogPO, SQ2.2 (or 4.4)q12h (4.4 mg/kg: q24h)22 mg (or 44 mg)
EnrofloxacinDogIM, PO, IV5-20q24h50-200 mg
PhenobarbitalDogPO2-8q12h20-80 mg

Common Veterinary Conversion Formulas

CalculationFormulaUsed for
Dose (mg)Weight (kg) × Dose rate (mg/kg)Total amount of drug from body weight
Volume of a liquid (mL)Dose (mg) ÷ Concentration (mg/mL)How much to draw up for an injection or oral liquid
Pounds to kilogramskg = lb ÷ 2.205Converting body weight
Fluid rate (mL/h)Weight (kg) × Rate (mL/kg/h)IV fluid pump rate per hour
Resting energy (kcal/day)70 × Weight (kg)0.75Daily energy needs for nutritional support
Body surface area (m²)K × Weight (g)2/3 ÷ 10,000 (K = 10.1 dogs, 10.0 cats)Dosing anticancer drugs in mg/m²

Frequently Asked Questions

Why are dosage rates different for each species?

Animals metabolize drugs differently because of differences in size, liver and kidney function and physiology. Cats, for example, are more sensitive to many NSAIDs than dogs, so a dose that is safe for one species can be harmful to another.

Can pet owners use these calculators safely?

Yes, as a reference for medicines your veterinarian has prescribed. Always confirm the dose with your veterinarian, because age, health problems and other medicines can change the right dose.

What if I know the weight in pounds?

Every calculator has a kg / lb switch next to the weight field. Pounds are converted to kilograms automatically (1 kg = 2.205 lb).

Do the calculators account for age or health conditions?

No. They use the standard doses listed in the handbook. Puppies and kittens, older animals and animals with liver, kidney or heart disease may need a different dose, which your veterinarian will decide.

How do I turn the dose into millilitres or tablets?

The calculators give the total dose (usually in mg). Divide it by the strength of your product: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL), or number of tablets = Dose (mg) ÷ mg per tablet.

Are horses and livestock included?

Yes. Where the handbook lists a dose, calculators include horses, cattle, sheep, goats and pigs. Withdrawal times for meat and milk depend on the product and country, so always follow the label.

How often should the dose be given?

Each result shows the dosing interval listed in the handbook, for example q12h (every 12 hours). Follow your veterinarian’s instructions for how long to continue treatment.

Is the result a single dose or a daily total?

The result is the amount for one dose. For a daily total, multiply it by the number of doses per day (for example × 2 for q12h).

Where do the doses come from?

Every calculator uses the doses published in the Saunders Handbook of Veterinary Drugs, and each page shows the handbook page number and the full dosage table.

Are emergency drugs included?

Yes, calculators are available for emergency drugs such as epinephrine, atropine and lidocaine. In an emergency these drugs must only be given by, or under the direction of, a veterinarian.

Medical Disclaimer

VetDosing calculators are an educational reference based on the Saunders Handbook of Veterinary Drugs. They do not replace a veterinary examination, diagnosis or prescription. Approved uses, product strengths and withdrawal times differ between products and countries. Not for human use.