How old is a 15 year old dog in human years?
A 15 year old dog is between 76 and 115 in human years, depending on size. A small dog comes to 76, a medium dog 83, a large dog 93 and a giant dog 115.
Size-based chart, medium dog
- Research formula (2020)
- 74
15 year old dog in human years by size
| Dog size | Human years | Next year | Roughly like |
|---|---|---|---|
| Small | 76 | +4 | a person in their mid 70s |
| Medium | 83 | +5 | a person in their early 80s |
| Large | 93 | +5 | a person in their early 90s |
| Giant | 115 | +7 | a person in their mid 110s |
After the second year the size matters. Between 15 and 16 a small dog gains 4 human years and a giant dog gains 7. The 2020 research formula gives 74, below the range from the size chart. Few giant dogs reach this age, so the giant figure is an extension of the chart.
Dog age against human age
The dots mark a 15 year old dog. Big dogs climb faster after the first two years.
Ages around 15
| Dog age | Small | Medium | Large | Giant | Research formula |
|---|---|---|---|---|---|
| 13 | 68 | 74 | 82 | 100 | 72 |
| 14 | 72 | 78 | 88 | 108 | 73 |
| 15 | 76 | 83 | 93 | 115 | 74 |
| 16 | 80 | 88 | 98 | 122 | 75 |
Compared with the old rule
The old rule of seven human years for each dog year would make a 15 year old dog 105. The size chart gives 76 to 115, so the old rule is inside the range here. Dogs age fast early on and then more slowly, and bigger dogs age faster later in life.
Questions
How old is a 15 year old small dog in human years?
About 76. Small dogs age more slowly in later years than large ones.
How old is a 15 year old large dog in human years?
About 93, and a giant dog comes to 115.
How old is a 15 year old dog if I do not know the size?
Use the size your dog will be as an adult. If you are unsure, the medium result of 83 is a fair middle guess.
What is 83 human years in dog years?
For a medium dog that is about 15 years. Try the human years to dog years calculator for any age.
Is this exact?
No. It is a general guide based on veterinary charts, and each dog ages differently. Your vet can say what the stage of life means for your dog's care.
Other dog ages
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
For any age and a size of your own, use the dog years to human years calculator. For cats see cat years to human years.
Sources
- American Animal Hospital Association (AAHA), canine and feline age chart, human-year equivalents by dog size.
- Wang T. et al., "Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome", Cell Systems, 2020 (University of California San Diego).
Last reviewed 2026-10-26.