A dog year was never seven human years.
One dog year is not seven human years. A one-year-old dog can reproduce; a seven-year-old child cannot. The ×7 rule fails in the first year and never recovers. Below are the two honest methods, printed whole before you enter anything. Then the number becomes the thing that matters: a life stage, and its work.
Method one · the headline figure
The size-adjusted table
The first dog year counts 15 human years and the second brings the total to 24. From year three, size takes over, because small dogs age slower than big ones. AVMA and AKC derived, and the whole rate card is here:
| Size | Boundary | Per year, after year two | Senior begins |
|---|---|---|---|
| Small | under 10 kg | +4 human years | around 10.5 years |
| Medium | 10 to 23 kg | +5 human years | around 8.6 years |
| Large | 23 to 40 kg | +6 human years | around 7.1 years |
| Giant | over 40 kg | +7 human years | around 6 years |
Method two · the comparison figure
The epigenetic clock
In 2020 researchers read ageing straight off DNA methylation in Labradors and matched it to humans. The formula is one line:
human age = 16 × ln(dog years) + 31
It calls young dogs older and old dogs younger than the table does, it was derived from one breed, and under 6 months the logarithm misbehaves, so there the study's own milestone mapping stands in. The reading below prints both figures side by side, because the disagreement between them is the honest state of the science.
The real output
Four stages, by AAHA's 2019 guidelines
- PuppyBirth to the end of rapid growth, 10 to 18 months, later in bigger dogs
- Young AdultEnd of growth to full physical and social maturity, about year three to four
- Mature AdultMaturity until the last quarter of expected lifespan begins
- SeniorThe last 25% of expected lifespan for that size or breed
Read your dog's age
Three facts. No signup, nothing stored, and the reading appears on this page, not behind a wall.
Asked often
- Is one dog year really seven human years?
- No. A one-year-old dog is roughly a 15-year-old human, not a 7-year-old child. The rate then slows, and it slows differently by size: small dogs add about 4 human years per dog year after year two, giant breeds about 7. The x7 rule fails in the first year and never recovers.
- Why do the two methods disagree?
- The size-adjusted table averages observed lifespans across sizes. The epigenetic clock reads DNA methylation, which moves fast in youth and slows late, so it calls young dogs older and old dogs younger than the table does. It was also derived from Labradors only. The disagreement is honest, which is why both numbers are printed.
- When does a dog become a senior?
- When the last quarter of expected lifespan begins, which depends on size: giant breeds around six years, large around seven, medium around eight to nine, small around ten to eleven. A Great Dane and a Pomeranian at seven are at completely different life stages.
- Do small dogs really live longer than big dogs?
- Yes, and it is one of the strongest patterns in dog biology. Small, long-nosed breeds live longest; giant breeds age fastest; and flat-faced breeds carry roughly 40% higher risk of a shorter life than average.
- How accurate is this for an Indie?
- Indies are commonly cited at 10 to 14 or more years, often outliving similar-sized pedigree dogs, but no published actuarial tables exist for them. This calculator treats the Indie figure as an estimate and says so, which is more honest than pretending precision.
- This is an educational reading, not a clinical assessment. Lifespan figures are population estimates; your dog is an individual, not an average.
- Every figure this page charges is printed above the form, so you can check the arithmetic yourself.
- Nothing is stored. The reading lives in its link and nowhere else.
A free tool from OhMyDog.Rocks.