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Dog age calculator: how old is my dog in human years?
Multiply your dog's age by seven? It's not that simple. Enter your dog's age and size, and the calculator will show their approximate age in human years and their current life stage.
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From puppyhood to a grey muzzle, every age has its own face. If you'd like to capture this time, your favourite photo can become a portrait.
View dog portraitsWhy multiplying by seven doesn't work
The old rule of thumb that one dog year equals seven human years is persistent. It's simple, but it doesn't really fit any dog. Dogs mature very quickly in their first year. A one-year-old dog is physically at roughly the same stage as a 15-year-old person. The second year adds around another nine human years. After that, things slow down, and size becomes the main factor.
Small dogs age gradually after their first few years; large and giant dogs age faster. According to the table, a ten-year-old Chihuahua is therefore about as old as a person in their mid-fifties. A ten-year-old Great Dane is already close to eighty. That's why the calculator asks about size as well as age.
How the dog age calculator works
It uses the American Kennel Club's table ‘How Old Is My Dog in Human Years?’. This divides dogs into four size categories and gives an equivalent human age for each year from 1 to 16. The weight limits are given in pounds; we have rounded them to kilograms. For half-years, we interpolate evenly between two table values. Below one year, we use the appropriate proportion of the first year; above 16 years, we continue the table's final yearly increment.
The life stage is based on age in years, rather than human years. A dog is considered a senior in the last quarter of their expected lifespan. The American Veterinary Medical Association gives rough guidelines of 8 to 11 years for small dogs, 8 to 10 for medium dogs, 8 to 9 for large dogs and 6 to 7 for giant dogs. The calculator uses the lower threshold in each case.
What the result tells you and what it doesn't
Human years are an illustration, not a diagnosis. They help put your dog's age into perspective: why a two-year-old still has plenty of mischief in mind despite looking fully grown, or why your large dog needs a little more rest at seven than your neighbour's Dachshund of the same age.
The number says nothing about your dog's health. Breed, weight, exercise, food and genetics all play a part, and every dog is different. A fit twelve-year-old can be more agile than a sluggish six-year-old. If anything changes, such as difficulty getting up, drinking more or eating less, your vet is the right person to consult, rather than the table.
What matters at each life stage
Puppyhood is about sleep, trust and small learning steps. During adolescence, your dog tests boundaries, and clear, kind rules will see you through this stage. Adult dogs need activity suited to their breed and a food allowance suited to their body condition. Our feeding calculator can help. In the senior years, walks become shorter and more frequent, beds softer and check-ups more regular.
Sometimes the result is simply a moment to pause. Noticing how quickly the years have passed is a good reason to make the most of your time together.
Common questions about dog age
Is one dog year really equal to seven human years?
No. Dogs age much faster in the first year and then at different rates depending on size. A one-year-old dog is roughly equivalent to a 15-year-old person, and a two-year-old to around 24. After that, each year adds roughly 4 to 7 human years, depending on size.
Why does size matter?
Large and giant dogs have shorter average lifespans and are considered seniors earlier. That's why the table uses larger increments for them than for small dogs from the sixth year onwards.
When does my dog become a senior?
The American Veterinary Medical Association gives rough guidelines of 8 to 11 years for small dogs, 8 to 10 for medium dogs, 8 to 9 for large dogs and 6 to 7 for giant dogs. The calculator uses the lower threshold in each case. Your dog may seem younger or older.
How accurate is the dog age calculator?
It provides a guide based on a widely used table. Every dog ages differently. Your vet is the right person to speak to about your dog's health.
Sources: American Kennel Club, the table ‘How Old Is My Dog in Human Years?’ in the article How to Calculate Dog Years to Human Years, accessed on 20.10.2026. Senior age thresholds: American Veterinary Medical Association, Caring for senior cats and dogs, accessed on 20.10.2026.