Dog Age Calculator
A dog's age in human-equivalent years by the epigenetic formula, with the old seven-year rule for comparison.
Results
What this tool does
The primary result uses the relationship published in 2020 from DNA methylation comparisons, 16 × ln(age) + 31, which was fitted to Labrador retrievers. The last result shows how many human-equivalent years the coming twelve months will add — a number that shrinks steadily as a dog gets older.
Formula
human age equivalent = 16 × ln(dog age) + 31
Variables
| Symbol | Meaning | Unit |
|---|---|---|
ag | Dog's age | a |
HA | Human-equivalent age | a |
OL | Human-equivalent age | a |
MO | Months | — |
NX | Human-equivalent age | a |
Worked example
- Dog's age5 a
- Human-equivalent age56.8 a
- Human-equivalent age33.0 a
- Months60
- Human-equivalent age2.92 a
Limitations
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.
Frequently asked questions
Which of the two numbers should I believe?
The first comes from a 2020 study that compared chemical marks on dog and human DNA and fitted a logarithmic curve to the match. It captures something the old rule misses entirely: dogs age extremely fast at first and then slow down, so a one-year-old dog is already closer to a thirty-year-old person than to a ten-year-old. The second is the familiar rule of thumb, shown for comparison. Both ignore breed, and size affects canine lifespan enormously — a great dane ages far faster than a terrier.