Dogs move through four broad life stages. Knowing which one your dog is in tells you most of what you need about its care.
Puppy
From birth to about one year. This is the steepest, fastest stretch of a dog’s whole life — a six-month puppy is already around ten human years old. Puppies need socialisation, gentle but consistent training, and a diet built for growth. For big breeds, do not over-exercise a growing puppy; the joints are still forming.
Adolescent
Roughly one to two years. The “teenager” phase — physically near full size but still mentally immature. Expect some testing of boundaries. Keep training steady and patient; this stage passes.
Adult
From about two years to the start of the senior stage. The long, stable middle of a dog’s life. The main job here is prevention: keep the dog lean, keep it active, keep up with vet checks. A lean adult dog is buying itself extra good years.
Senior
When the senior stage begins depends entirely on size — around 10 for a small dog, as early as 5 or 6 for a giant breed. Senior is not a warning; it is just a stage. Adjust for comfort: softer beds, gentler exercise, vet checks that watch joints and weight.
Finding your dog’s stage
Because the timeline shifts with size, the clearest way to place your dog is the dog age calculator — it tells you both the human-year number and which stage your dog is in. You can also check the typical lifespan for your dog on its breed page.