Dog age calculator

How to use the dog age calculator

1. Age. Type your dog’s age in years and months. For a puppy under one, leave years at 0 and fill in the months.
2. Size. Tap small, medium, large or giant. Go by your dog’s adult weight. For a mixed breed, use the weight your vet expects when fully grown.

The result shows your dog’s age in human years and a life stage: puppy, young adult, adult or senior. You also see what the rule of 7 would have said, so you can compare.

Which size is my dog?

• Small: up to about 9 kg (20 lb). Chihuahua, Dachshund, Shih Tzu, Pug.
• Medium: about 10 to 23 kg (21 to 50 lb). Beagle, Border Collie, Cocker Spaniel.
• Large: about 24 to 45 kg (51 to 100 lb). Labrador, Golden Retriever, German Shepherd.
• Giant: over 45 kg (100 lb). Great Dane, Mastiff, Saint Bernard.

How dog years to human years are worked out

Dogs grow up fast and then age more slowly. Bigger dogs age faster than smaller dogs once they are adults. The widely published size-based chart reflects both facts.

Year 1 = 15 human years. Year 2 adds 9, so a 2 year old dog is 24. Each year after that adds 4 (small), 5 (medium), 6 (large) or 7 (giant).

For a puppy under one, the calculator spreads the first 15 human years evenly across 12 months.

Worked example

A Labrador is 5 years and 6 months old. A Labrador is a large dog, so each year after the second adds 6.

• First two years: 15 + 9 = 24 human years.
• Time after age 2: 5.5 − 2 = 3.5 years.
• Extra human years: 3.5 × 6 = 21.
• Human-equivalent age: 24 + 21 = 45.

The rule of 7 would give 5.5 × 7 = 38.5, which is more than six years lower.

Dog age chart by size

Find your dog’s age on the left and read across to its size. All figures are human-equivalent years.

Dog’s age	Small	Medium	Large	Giant
1 year	15	15	15	15
2 years	24	24	24	24
3 years	28	29	30	31
4 years	32	34	36	38
5 years	36	39	42	45
6 years	40	44	48	52
7 years	44	49	54	59
8 years	48	54	60	66
9 years	52	59	66	73
10 years	56	64	72	80
11 years	60	69	78	87
12 years	64	74	84	94
13 years	68	79	90	101
14 years	72	84	96	108
15 years	76	89	102	115
16 years	80	94	108	122

Why multiplying by 7 is inaccurate

The rule of 7 assumes a dog ages at one steady rate for its whole life. It does not.

• The first year is far more than 7. Many dogs are close to fully grown and able to breed at one year old. A 7 year old child is not. Fifteen human years is a closer match.
• Size changes the pace. Small breeds tend to live longer than giant breeds. One multiplier cannot fit both a Chihuahua and a Great Dane.
• The gap grows with age. At 10, the rule of 7 says 70 for every dog. The chart says 56 for a small dog and 80 for a giant one.

Life stages in this calculator

The life stage comes from the human-equivalent age: puppy below 15, young adult from 15, adult from 30 and senior from 56. On that scale a small dog is a senior at about 10 years, a medium dog a little after 8, a large dog a little after 7 and a giant dog at about 6 and a half.

Treat every figure here as an estimate. Breed, weight, diet and health all change how an individual dog ages. Your vet can tell you when to move to senior food or senior check-ups.

For people, use the age calculator or the baby age calculator. To count the days since an adoption date, try days between dates.

How this calculator was checked

Built by Rasel Hakkani, WordPress developer at Swift Web Dev. The results were checked against the chart on this page for every size and for ages from 4 months to 16 years. The life stages are a rule used by this calculator, not a veterinary standard.

Sources

• American Kennel Club: How to Calculate Dog Years to Human Years, which gives the American Veterinary Medical Association guideline of 15 human years for the first year, 9 for the second and about 5 for each year after

Last checked: October 2026. Found a wrong answer? Tell us and we will fix it.