Dog Age Chart

Human-year equivalents for every dog age from 2 months to 20 years, broken down by breed size. Based on peer-reviewed veterinary research.

Want an instant result for your dog's exact age?

The calculator handles decimals and months — no chart-reading required.

Use Calculator

Complete Dog Age Chart

Numbers = approximate human-year equivalent. Based on peer-reviewed research with breed-size multipliers.

Dog age	Small< 10 kg	Medium10–25 kg	Large25–45 kg	Giant> 45 kg
2 months(puppy)	2	3	3	3
3 months(puppy)	3	4	4	5
6 months(puppy)	7	8	9	10
9 months(puppy)	10	11	13	15
1 year(puppy)	28	31	36	40
2 years	38	42	48	55
3 years	44	49	56	63
4 years	48	53	61	69
5 years	51	57	65	74
6 years	54	60	69	78
7 years	56	62	71	81
8 years	58	64	74	84
9 years	60	66	76	86
10 years	61	68	78	88
11 years	62	69	80	90
12 years	64	71	81	92
13 years	65	72	83	94
14 years	66	73	84	95
15 years	67	74	85	97
16 years	68	75	87	98
17 years	69	76	88	99
18 years	70	77	89	100
19 years	70	78	90	102
20 years	71	79	91	103

Values rounded to nearest integer. Puppy rows (italic) use linear approximation; adult rows use Wang logarithmic formula.

How to Use This Chart

1Find your dog's age in the leftmost column. Puppies under 1 year are shown in months.
2Determine your dog's breed size: Small (< 10 kg), Medium (10–25 kg), Large (25–45 kg), Giant (> 45 kg).
3Read the number at the intersection — that's their approximate human-year equivalent.
4Use the result to contextualize their life stage, not as a medical diagnosis.

Life Stage Milestones

The chart numbers become more useful when mapped to life stages. As a general rule using Harvey 2021 behavioral stages:

Stage	Dog age	Human equivalent
Puppy	0–6 months	Infant
Juvenile	6–12 months	Pre-teen
Young Adult	1–2 years	Teenager
Mature Adult	2–7 years	Adult
Early Senior	7–10 years	Middle-aged
Late Senior	10–12 years	Senior
Geriatric	12–15 years	Elderly
Very Aged	15+ years	Centenarian

Large and giant breeds reach senior status 2–4 years earlier than small breeds at the same chronological age. See our signs of aging in dogs guide for what to watch for at each stage.

Frequently Asked Questions

Find your dog's age in the left column, then look across to the column matching their breed size (Small, Medium, Large, or Giant). The number shown is the approximate human-year equivalent based on peer-reviewed veterinary research.

Small: under 10 kg (Chihuahua, Pomeranian, Maltese). Medium: 10–25 kg (Beagle, Bulldog, Border Collie). Large: 25–45 kg (Labrador, Golden Retriever, German Shepherd). Giant: over 45 kg (Great Dane, Mastiff, Saint Bernard).

Dogs undergo rapid developmental changes in their first two years — equivalent to human childhood and adolescence. After year 2, the rate of biological aging slows considerably, which is why each additional dog year adds fewer human-year equivalents in the table.

It's an approximation. Within a size category, individual breeds can vary by 2–4 years. For example, within 'Large', a Border Collie typically lives longer than an English Bulldog. The chart uses best-available size-based averages.

More accurate than the ×7 rule, but still an approximation. Exact biological age depends on genetics, diet, veterinary care, and environment. The formula was derived from Labrador Retrievers; the size multipliers extend it to other sizes based on lifespan data.

Approximately 15 human years for all sizes. At 1 year, a dog has already reached sexual maturity and has adult teeth — developmentally comparable to a mid-teenage human.

About This Chart

Values are calculated using the Wang et al. 2020 epigenetic aging formula with size multipliers derived from published breed lifespan data. The same formula powers the Dog Age Calculator.

PawToolkit provides general information only. Always consult a licensed veterinarian for medical advice specific to your pet.