How old is my dog in dog years?

Nearly all dog owners sometimes wonder how old their dog would be if they were a human. There are lots of different theories about this, but just how do you work it out?

How old is my dog if they were a human?

It used to be thought that you could work out your dog’s age in human years by multiplying by seven, but we know now that isn’t the case and it depends on your dog’s size and breed/type.

PetMD give a really useful chart that will help you calculate your dog’s age depending on their size and weight. As you can see, giant dogs have a shorter lifespan than smaller ones – and a small 12-year-old dog would only be 64 and not even eligible for their pension, while a 12-year-old giant dog would be the equivalent of 93 years old.

Signs of ageing in dogs

While it’s fun to work out how old your dog would be if they were human, the best thing you can do to maintain your dog’s health is to keep an eye on the visible signs of ageing when living with an older dog.

Just like humans, lots of dogs will start to get grey or white hairs appearing.
Eyes may start to appear cloudy, and your dog may develop cataracts.
Teeth may become more yellow with visible plaque and become more damaged as your dog gets older – showing the importance of canine dental care throughout your dog’s life.
Behavioural changes – as your dog slows down with age, you may find they are calmer and less active than when they were younger. Some dogs begin to show signs of confusion, disorientation, loss of toilet training and change of sleep patterns. This could indicate they have Canine Cognitive Disfunction (similar to dementia). If you see any of these changes, talk to your vet straight away as there are medications that can slow the onset of these symptoms.
As they become a little less active, older dogs’ weight and body condition need to be monitored. If your dog is starting to struggle with stairs or not as excited about going for a walk as they used to be, this is a real sign they are growing older. It is important to adapt their exercise routine accordingly – so instead of one long walk a day that can tire muscles and joints, take several shorter walks. Also stop playing any games that involves sudden starts, stops and turns (such as throwing balls).

As your dog grows older, you may want to move them on to a senior food, and continue with regular vet check-ups to keep them as fit and healthy as you can. If you notice any new changes – physically or behaviourally – contact your vet straight away.

Last reviewed by expert behaviourist Carolyn Menteith on 7 July 2024.