Shih Tzu Age Calculator
How old is your Shih Tzu
in human years?
Shih Tzus are flat-faced, yet they outlive most flat-faced breeds and match the average dog. This calculator uses the breed's own lifespan from a 2024 study of 584,734 UK dogs.
By Claire Whitman · Updated · Sources
By Breed set to Shih Tzu. Different breed? Use the main dog age calculator.
Human age equivalent
51years
Your dog is in the long middle stretch of adulthood. Continue annual wellness exams with baseline bloodwork, monitor for subtle weight or behavior changes, and watch for early signs of chronic conditions such as dental disease, arthritis, or weight gain (AAHA 2019).
An estimate based on Wang et al. (2020) for the first two years, then scaled so a Shih Tzu turns senior at about 9.6 years, the last quarter of its 12.8-year median lifespan (McMillan et al. 2024). Individual dogs vary. Not veterinary advice.
Shih Tzu age chart: Shih Tzu years to human years
Find your Shih Tzu's age on the left and read across. The right column is our standard estimate for a dog under 20 lbs, the one the main calculator uses. It turns senior at 12, over two years later than a Shih Tzu's breed-based senior age: a 10-year-old Shih Tzu is about 66 in human years, against 60 for a typical small dog.
| Dog age | Shih Tzu | Typical small dog under 20 lbs |
|---|---|---|
| 1 year | 31 | 31 |
| 2 years | 42 | 42 |
| 3 years | 45 | 44 |
| 4 years | 48 | 47 |
| 5 years | 51 | 49 |
| 6 years | 54 | 51 |
| 7 years | 57 | 54 |
| 8 years | 60 | 56 |
| 9 years | 63 | 58 |
| 10 years | 66 | 60 |
| 11 years | 69 | 63 |
| 12 years | 72 | 65 |
| 13 years | 75 | 67 |
| 14 years | 78 | 70 |
| 15 years | 81 | 72 |
| 16 years | 84 | 74 |
Shaded cells: senior life stage (the last quarter of expected lifespan, AAHA 2019).
When is a Shih Tzu considered a senior?
At about 9 and a half years old. The 2019 AAHA life stage guidelines define the senior stage as the last 25% of a dog's estimated lifespan rather than a fixed age. The largest study of UK dogs so far put the Shih Tzu's median lifespan at 12.8 years, and 75% of 12.8 is 9.6. Our main calculator uses 12 for dogs under 20 lbs.
Senior doesn't mean sick. It's the stage where vets usually move from yearly to twice-yearly checkups, so changes are caught early. Ask your vet when they'd like to start for your dog.
How long do Shih Tzus live?
Published figures run from about 10 to 18 years. The studies themselves sit closer together.
- 12.8 years (median): McMillan et al. (2024) combined records for 584,734 UK dogs, including 12,007 Shih Tzus. Half lived past 12.8 years. The median for all dogs was 12.5.
- 12.7 years (median age at death): Dale et al. (2024) reviewed 85 Shih Tzus with a recorded age at death under UK vet care. The oldest was 19.9.
- 11.05 years (life expectancy at birth): Teng et al. (2022) built life tables from about 635 Shih Tzus that died at UK vet practices, close to the 11.23 they found for dogs overall.
- 10 to 18 years (breed range): the wide range the American Kennel Club lists. It isn't a measured average.
We compare the Shih Tzu with other flat-faced breeds in Shih Tzu lifespan: a flat-faced breed that lives long.
Eyes and teeth in aging Shih Tzus
In a UK study of vet records, 11.9% of Shih Tzus had an eye problem diagnosed in one year, and both dry eye and corneal ulcers were more common after age 7. Periodontal (gum) disease was the most common single diagnosis at 9.5%, and it also rose with age. Mention any change in your dog's eyes at the vet promptly, and ask about teeth at each checkup.
How we calculate Shih Tzu age
- First two years: the formula from Wang et al. (2020, Cell Systems), human_age = 16 × ln(dog_age) + 31, the same for every dog. A 1-year-old Shih Tzu is about 31 in human years and a 2-year-old about 42.
- After age 2: a steady pace set so a Shih Tzu reaches 65 human years when it turns senior at about 9.6. That's about 3.0 human years per year, against 2.3 for a typical small dog. It puts a Shih Tzu at the 12.8-year median at about 75, the same point every size reaches at its typical lifespan in our main calculator.
The small-dog default assumes a senior age of 12, which matches a lifespan of about 16 years. A Shih Tzu's measured median is shorter than that, so we use the breed's own number.
Frequently asked questions
How old is a 5-year-old Shih Tzu in human years?
About 51. By the same method, a typical small dog would be about 49. The chart above shows every age from 1 to 16.
How old is a 10-year-old Shih Tzu in human years?
About 66. Ten is just past the age of about 9.6 when a Shih Tzu enters the senior stage.
When is a Shih Tzu considered a senior?
From about 9 and a half. AAHA treats the last 25% of a dog's expected lifespan as the senior stage, and the median lifespan for Shih Tzus is 12.8 years.
How long do Shih Tzus live?
The largest study, of 584,734 UK dogs, found a median lifespan of 12.8 years for Shih Tzus, against 12.5 for all dogs. The American Kennel Club lists a wider range of 10 to 18 years.
Does the "1 dog year = 7 human years" rule work for Shih Tzus?
No. A 1-year-old Shih Tzu is already about 31 in human years. After age 2, Shih Tzus add about 3.0 human years for each calendar year.
Sources
- McMillan KM, Bielby J, Williams CL, Upjohn MM, Casey RA, Christley RM (2024). Longevity of companion dog breeds: those at risk from early death. Scientific Reports 14: 531. doi:10.1038/s41598-023-50458-w
- Dale F, Brodbelt DC, West G, Church DB, Lee YH, O'Neill DG (2024). Demography, common disorders and mortality of Shih Tzu dogs under primary veterinary care in the UK. Canine Medicine and Genetics 11: 2. doi:10.1186/s40575-023-00135-y
- Teng KT, Brodbelt DC, Pegram C, Church DB, O'Neill DG (2022). Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom. Scientific Reports 12: 6415. doi:10.1038/s41598-022-10341-6
- Wang T, et al. (2020). Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome. Cell Systems 11(2): 176–185. doi:10.1016/j.cels.2020.06.006
- Creevy KE, et al. (2019). 2019 AAHA Canine Life Stage Guidelines. Journal of the American Animal Hospital Association 55(6): 267–290. doi:10.5326/JAAHA-MS-6999
- American Kennel Club. Shih Tzu breed profile.