Convert your dog's chronological age into biological human years.
Small (20 lbs or less)
Medium (21-50 lbs)
Large (51-90 lbs)
Giant (Over 90 lbs)
Equivalent Human Age:
Understanding Your Dog's Biological Age
For decades, many pet owners followed the "7-year rule"—the idea that one dog year equals seven human years. However, modern veterinary science has proven this to be an oversimplification. Dogs age much faster in their first two years of life, and their eventual rate of aging depends significantly on their breed size.
How the Dog Age Calculation Works
Our calculator uses the revised methodology accepted by the American Veterinary Medical Association (AVMA). The first year of a medium-sized dog's life is roughly equal to 15 human years. The second year adds about nine human years. After the age of two, the aging process stabilizes, but the speed varies by size:
Small Breeds: Age approximately 4 human years for every calendar year.
Medium Breeds: Age approximately 5 human years for every calendar year.
Large Breeds: Age approximately 6 human years for every calendar year.
Giant Breeds: Age approximately 7 human years for every calendar year.
Why Size Matters
Smaller dogs generally have longer lifespans than larger breeds. A Great Dane is considered a senior at 6 or 7 years old, while a Chihuahua might not reach that milestone until 10 or 11. This biological discrepancy is why a size-specific calculation is essential for accurate health monitoring.
Dog Age
Small Human Age
Medium Human Age
Large Human Age
Giant Human Age
1 Year
15
15
15
12
2 Years
24
24
24
22
5 Years
36
37
40
45
10 Years
56
60
66
78
Example Calculations
If you have a 5-year-old Golden Retriever (Large Breed), the calculation looks like this: The first two years equal 24 human years. The remaining 3 years are multiplied by 6 (Large breed rate). Total: 24 + (3 * 6) = 42 human years.
Conversely, a 5-year-old Toy Poodle (Small Breed) would be: 24 + (3 * 4) = 36 human years.
function calculateDogAge() {
var dogAge = parseFloat(document.getElementById('dogAgeInput').value);
var dogSize = document.getElementById('dogSizeSelect').value;
var resultDiv = document.getElementById('dogResult');
var resultText = document.getElementById('humanAgeResult');
var humanAge = 0;
if (isNaN(dogAge) || dogAge < 0) {
alert("Please enter a valid age.");
return;
}
if (dogAge === 0) {
humanAge = 0;
} else if (dogAge <= 1) {
// Year 1 is special
if (dogSize === "giant") {
humanAge = dogAge * 12;
} else {
humanAge = dogAge * 15;
}
} else if (dogAge <= 2) {
// Year 2 logic
var firstYear = (dogSize === "giant") ? 12 : 15;
var secondYearRate = (dogSize === "giant") ? 10 : 9;
humanAge = firstYear + ((dogAge – 1) * secondYearRate);
} else {
// 2+ years logic
var baseAge = (dogSize === "giant") ? 22 : 24;
var multiplier = 4;
if (dogSize === "small") {
multiplier = 4;
} else if (dogSize === "medium") {
multiplier = 5;
} else if (dogSize === "large") {
multiplier = 6;
} else if (dogSize === "giant") {
multiplier = 7;
}
humanAge = baseAge + ((dogAge – 2) * multiplier);
}
resultText.innerHTML = Math.round(humanAge * 10) / 10 + " human years";
resultDiv.style.display = "block";
}