Dog Age Calculator
Convert your dog's age into human years based on breed size with this free dog age calculator that works right in your browser.
Enter Values
Minimum 0
How to use this calculator
- Enter your dog's age in years (use a decimal like 0.5 for 6 months).
- Read the human-equivalent age.
How it works
It uses the widely-used chart rather than the outdated 'multiply by 7' rule: the first year counts as about 15 human years, the second adds about 9 (to 24), and each year after adds roughly 5.
So a 5-year-old dog is about 24 + 3 × 5 = 39 human years.
Worked example
A 5-year-old dog. ≈ 39 human years.
Common mistakes
- Using the old '1 dog year = 7 human years' rule — dogs mature much faster in their first two years.
- Ignoring breed size — small dogs generally age more slowly and live longer than large breeds, so treat this as a guide.
Frequently asked questions
Is the '×7' rule accurate?
No — it's a myth. Dogs age quickly early on (a 1-year-old is more like a teenager) then slow down, which is why this tool uses a staged chart.
Does breed or size change the answer?
Yes. Smaller breeds tend to age more slowly and live longer than large breeds, so the figure is a general estimate rather than an exact age.
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Cite this tool
Zerdly. (2026). Dog Age Calculator. Retrieved from https://www.zerdly.com/tools/dog-age-calculator/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.