Convert your dog's calendar years into equivalent human years based on size and breed characteristics.
Small (20 lbs or less)
Medium (21-50 lbs)
Large (51-90 lbs)
Giant (Over 90 lbs)
Your dog's human age is approximately:
The Science of Dog Years vs. Human Years
The old "one dog year equals seven human years" rule is a common myth. In reality, dogs age much faster during their first two years of life, and their aging process slows down or accelerates later based on their physical size and breed. Smaller dogs generally live longer and age more slowly than giant breeds.
How We Calculate Dog Age
This calculator uses the revised formulas commonly accepted by veterinarians:
The First Year: Most dogs, regardless of size, reach the equivalent of 15 human years in their first calendar year.
The Second Year: The second year adds approximately 9 human years, bringing a two-year-old dog to roughly 24 human years.
The Mature Years: After age two, the aging rate depends on the dog's weight category. Small dogs age about 4 human years per calendar year, while giant breeds can age up to 7 or 8 human years per calendar year.
Age Comparison Table
Calendar Years
Small (Human Years)
Medium (Human Years)
Large (Human Years)
Giant (Human Years)
1
15
15
15
12
2
24
24
24
22
5
36
37
40
45
10
56
60
66
79
Life Stages of Your Dog
Understanding your dog's human age equivalent helps you provide better care tailored to their life stage:
Puppyhood (0-18 months): Rapid growth and high energy. Focus on socialization and basic training.
Adulthood (2-6 years): Peak physical condition. Regular exercise and preventative health checkups are key.
Senior Years (7+ years): Larger dogs reach senior status earlier. Watch for joint issues, cognitive changes, and metabolic shifts. Adjust diet and increase the frequency of veterinary visits.
Realistic Examples
Consider a 5-year-old Beagle (Small/Medium). At 5 calendar years, they are approximately 36-37 human years old—firmly in their prime. Conversely, a 5-year-old Great Dane (Giant) is already 45 human years old, nearing the transition to their senior years.
function calculateDogAge() {
var dogAge = document.getElementById("dogAge").value;
var dogSize = document.getElementById("dogSize").value;
var humanAge = 0;
// Validate input
if (dogAge === "" || dogAge < 0) {
alert("Please enter a valid age.");
return;
}
var age = parseFloat(dogAge);
if (age <= 1) {
// Special logic for puppies under 1 year
humanAge = age * 15;
} else if (age 2) {
baseAge = 22;
}
}
humanAge = baseAge + (additionalYears * multiplier);
}
// Round to one decimal place
humanAge = Math.round(humanAge * 10) / 10;
// Display result
document.getElementById("humanAgeResult").innerText = humanAge + " Human Years";
document.getElementById("dogResult").style.display = "block";
}