Is this calculator a substitute for veterinary advice?

No. This tool is for informational and educational purposes only. Always consult a licensed veterinarian before giving any medication to your dog. Doses vary with the condition being treated, age, breed, liver and kidney function, pregnancy and other medications.

How much Benadryl (diphenhydramine) can I give my dog?

The Merck Veterinary Manual lists diphenhydramine at 2–4 mg/kg by mouth every 8–12 hours, which is roughly 1–2 mg per pound. A 25 lb (11.3 kg) dog would get about 23–45 mg. Use plain diphenhydramine only: products with a decongestant (pseudoephedrine, phenylephrine), acetaminophen or xylitol can poison dogs. Ask your vet first, especially for dogs with glaucoma, heart disease or seizures.

Can I give my dog ibuprofen, naproxen or Tylenol?

No, not without a veterinarian. Ibuprofen and naproxen have a narrow safety margin in dogs and cause stomach ulcers and kidney injury (Merck reports gastric ulceration in dogs given 8–16 mg/kg/day of ibuprofen for 30 days). Acetaminophen can damage the liver and red blood cells. Never combine a human NSAID with a veterinary NSAID such as carprofen or meloxicam, or with steroids. Call your vet or the ASPCA Animal Poison Control Center (888-426-4435) after any accidental ingestion.

What does mg/kg mean?

mg/kg stands for milligrams of drug per kilogram of body weight. For example, a dose rate of 5 mg/kg for a 10 kg dog means 50 mg per dose. To convert pounds to kilograms divide by 2.2046.

How do I convert the dose to mL of a liquid medicine?

Divide the dose in mg by the concentration on the label in mg/mL. A 150 mg dose of a 50 mg/mL liquid is 3 mL. Check the concentration on the exact bottle, because the same drug comes in different strengths, and never use human liquids that contain xylitol.

How many tablets should my dog get?

Divide the dose in mg by the tablet strength. A 44 mg carprofen dose with 25 mg tablets is 1.76 tablets, so your vet might prescribe 1¾ tablets or a different strength. Only split tablets that are scored or that your vet or pharmacist says can be split.

Why do some drugs show two dosing schedules?

Some labels allow either a smaller dose twice a day or a larger dose once a day (carprofen 2.2 mg/kg every 12 h or 4.4 mg/kg every 24 h). The daily total is the same; using the larger dose twice a day doubles it. The calculator flags daily totals above the published maximum.

Why do the reference doses show a range?

Many drugs have a therapeutic range rather than a fixed dose, and the right point depends on the condition and the dog. Your veterinarian chooses the dose and may adjust it based on response, blood levels (for example phenobarbital) or side effects.

Dog Medication Dosage Calculator

Enter your dog's weight and the dose rate your vet prescribed (mg/kg) to get the dose in mg, the number of tablets or mL of liquid, and the daily total, with sourced reference ranges and toxicity warnings.

Dog dose (mg) = body weight (kg) × dose rate (mg/kg), where 1 lb = 0.4536 kg.

Not veterinary advice. Give only medicines your veterinarian has prescribed for this dog, at the prescribed dose. Many human medicines are toxic to dogs. Suspected poisoning: call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.

Dose Calculator

Dog's Body Weight

Drug (optional)

Dose Rate (mg/kg per dose)

Doses per Day

Tablet strength (mg)

Liquid (mg/mL)

Disclaimer: For informational use only, not veterinary advice. Always confirm doses with a licensed veterinarian before administering any medication.

Enter weight and dose rate, or pick a drug from the list or the reference table below.

Canine Dose Reference (Published Ranges)

Click a row to load it into the calculator. Doses are per administration, by mouth, for the typical indication shown; your veterinarian may prescribe differently for your dog's condition.

Drug	Common Use	mg/kg	How Often	Source
Amoxicillin	Antibiotic (bladder infection)	11–15	every 12 h	ISCAID urinary guidelines
Amoxicillin-clavulanate	Antibiotic	13.75	every 12 h	Merck Vet Manual
Carprofen (twice daily)	NSAID, pain/arthritis	2.2	every 12 h	Merck Vet Manual
Carprofen (once daily)	NSAID, pain/arthritis	4.4	every 24 h	Merck Vet Manual
Meloxicam	NSAID, pain/arthritis	0.1	every 24 h	Merck Vet Manual; product label
Cephalexin	Antibiotic (skin)	20–30	every 12 h	Merck Vet Manual
Doxycycline (twice daily)	Antibiotic (respiratory)	5	every 12 h	ISCAID respiratory guidelines
Doxycycline (once daily)	Antibiotic (respiratory)	10	every 24 h	ISCAID respiratory guidelines
Enrofloxacin	Antibiotic	5–20	every 24 h	FDA label; Merck Vet Manual
Trimethoprim-sulfonamide	Antibiotic	15–30	every 12 h	Merck Vet Manual
Metronidazole	Diarrhea / antiprotozoal	10–15	every 12 h	Label dose (Ohio State antimicrobial guide)
Gabapentin	Nerve and chronic pain	5–10	every 8–12 h	Today's Veterinary Practice (Grubb)
Tramadol	Pain (opioid)	2–4	every 8 h	Licensed canine product label (UK VMD)
Omeprazole	Stomach acid reducer	0.5–1	every 24 h	Merck Vet Manual
Famotidine	Stomach acid reducer	0.5–1	every 24 h	Merck Vet Manual
Prednisolone (anti-inflammatory)	Steroid, allergy/inflammation	0.5–1	every 24 h	Merck Vet Manual
Phenobarbital	Seizures (starting dose)	2–4	every 12 h	Merck Vet Manual
Diphenhydramine (Benadryl)	Antihistamine, allergy	2–4	every 8–12 h	Merck Vet Manual
Cetirizine (Zyrtec)	Antihistamine, itch	1	every 12–24 h	Merck Vet Manual

Sources: Merck Veterinary Manual tables (NSAIDs, antihistamines, antistaphylococcal antimicrobials, antiulcer and antiepileptic drugs; prednisolone in hormonal therapy), ISCAID urinary and respiratory antimicrobial guidelines, and licensed product labels. Checked 2026-10-09.

Human Medicines That Are Dangerous for Dogs

Do not give these without a veterinarian's explicit instruction. There is no safe "dog dose" to calculate at home.

Ibuprofen (Advil, Motrin), naproxen (Aleve): Stomach ulcers, bleeding and kidney failure; narrow safety margin in dogs.
Acetaminophen (Tylenol), including combination cold/flu products: Liver injury and damaged red blood cells.
Decongestants: pseudoephedrine, phenylephrine ("-D" products): Racing heart, high blood pressure, tremors and seizures.
Xylitol-sweetened liquids, chewables and gums: Rapid low blood sugar and liver failure, even in small amounts.
A human NSAID plus carprofen, meloxicam or a steroid: Combining anti-inflammatories greatly raises ulcer risk.

Source: Merck Veterinary Manual, toxicities from human drugs. Accidental ingestion: call your vet or the ASPCA Animal Poison Control Center, (888) 426-4435.

Quick answer

Dog dose (mg) = body weight (kg) × dose rate (mg/kg), where 1 lb = 0.4536 kg. Example: a 44 lb (20 kg) dog prescribed carprofen at 2.2 mg/kg twice daily gets 44 mg per dose. Divide the mg dose by the tablet strength for tablets, or by the liquid's mg/mL for milliliters. Only give medicines your veterinarian has prescribed for your dog.

Examples

Drug (published dog range)	Dog weight	Dose per administration
Carprofen 2.2 mg/kg every 12 h	20 kg (44 lb)	44 mg
Diphenhydramine 2–4 mg/kg every 8–12 h	11.3 kg (25 lb)	23–45 mg
Cephalexin 20–30 mg/kg every 12 h	30 kg (66 lb)	600–900 mg
Gabapentin 10 mg/kg as prescribed	15 kg (33 lb)	150 mg = 1.5 mL of a 100 mg/mL compounded liquid

Pick the drug, enter weight and the prescribed mg/kg, and add tablet strength or liquid mg/mL to convert.

Summary

This calculator multiplies a dog's body weight by the drug's dose rate in mg/kg to give the dose in milligrams, then converts it to tablets or milliliters and a daily total. Reference ranges come from the Merck Veterinary Manual, ISCAID antimicrobial guidelines and veterinary product labels, and the tool warns when a daily total exceeds the published maximum. It is not veterinary advice: many human medicines are toxic to dogs, and the correct drug and dose depend on the diagnosis, age, organ function and other medicines.

How it works

Enter your dog's body weight in kilograms or pounds (1 lb = 0.45359237 kg).
Pick a drug from the list to load its published range and dosing interval, or type the mg/kg dose your veterinarian prescribed.
Choose how many times a day the dose is given; the daily total is checked against the published daily maximum where one exists.
Optionally enter the tablet strength (mg) to get tablets per dose, or the liquid concentration (mg/mL) to get milliliters per dose.
Always confirm the dose and the product with a licensed veterinarian before giving any medication.

Use cases

Check that a prescribed dose matches your dog's current weight.
Convert a mg dose into tablets or mL of a liquid formulation.
Look up published canine dose ranges with their sources.
See why two dosing schedules (e.g. carprofen 2.2 mg/kg twice daily vs 4.4 mg/kg once daily) must not be combined.
Educational reference for veterinary students learning pharmacology.
Help pet owners understand the math behind their vet's prescription.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu