Calculator
Melatonin dosage calculator.
Enter your dog’s weight in kg or lb. We’ll show the size-band dose vets commonly use, from Plumb’s, with the references visible. In the UK melatonin is prescription-only, so your vet sets the actual dose.
Read this first
Many human melatonin products contain xylitol — never give those to a dog.
Xylitol (sometimes labelled “birch sugar”) is severely toxic to dogs even in tiny amounts. Some also contain 5-HTP, which is toxic to dogs too. In the UK melatonin is prescription-only, so your vet will supply a product that is safe for dogs.
Your dog’s weight
Enter weight to find the dose band
Melatonin in dogs is dosed as mg per dog — not mg per kg — so the dose depends on size band rather than precise weight.
All four size bands
Reference table.
Small
Under 10kg / 22lb
Dose
0.5–1mg
Examples
Chihuahua, dachshund, Yorkshire terrier, miniature poodle
Medium
10–25kg / 22–55lb
Dose
1–3mg
Examples
Cocker spaniel, beagle, border collie, French bulldog
Large
25–40kg / 55–88lb
Dose
5mg
Examples
Labrador, golden retriever, German shepherd, boxer
Giant
Over 40kg / 88lb
Dose
5mg
Examples
Great Dane, Saint Bernard, Newfoundland, mastiff