Dog Age Calculator: Dog and Cat Years in Human Years

Free · No sign-up · Updated October 2026

Convert your dog's age to human years using the AVMA size-based chart, or your cat's using the AAHA/AAFP chart, with life stages and the full table.

My pet is a

Years

Months

Adult size

Use the weight your dog is (or will be) when fully grown. HDB flats allow one dog from the AVS list of approved small breeds, and most of those fall in the small band.

Your dog's age in human years

5 years old, medium dog

The old 7× rule says: 35
Each extra year now: about +6 human years

An estimate from a vet-association chart, not a medical age. Your vet judges ageing from health, weight and teeth.

Dog years chart

Human-year equivalents by adult size. Bigger dogs age faster after about age 5.

Dog age	Small	Medium	Large	Giant
1	15	15	15	12
2	24	24	24	22
3	28	28	28	31
4	32	32	32	38
5	36	36	36	45
6	40	42	45	49
7	44	47	50	56
8	48	51	55	64
9	52	56	61	71
10	56	60	66	79
11	60	65	72	86
12	64	69	77	93
13	68	74	82	100
14	72	78	88	107
15	76	83	93	114
16	80	87	99	121

How this works

Dogs age fastest at the start: the first year of a medium-sized dog's life is about 15 human years, the second adds about 9, and each year after that adds about 4 to 5. From around age 5, bigger dogs age faster, so this calculator uses the size-based dog years chart published by the American Veterinary Medical Association, with sizes of up to 9 kg (small), 9 to 23 kg (medium), 23 to 45 kg (large) and over 45 kg (giant). Ages between whole years are interpolated.

Cats follow the AAFP/AAHA feline life stage chart: 6 months is about 10 human years, 1 year is 15, 2 years is 24, and every year after that adds 4. The 2021 AAHA/AAFP guidelines group cats into kitten (up to 1 year), young adult (1 to 6), mature adult (7 to 10) and senior (over 10).

These are rough equivalents for comparing life stages, not a medical age. Breed, weight and health all change how a pet ages, so check-up and diet plans should come from your vet.

FAQs

How old is a 5-year-old dog in human years?

A 5-year-old small, medium or large dog is about 36 in human years, and a giant breed is about 45, on the AVMA chart.

Is one dog year really seven human years?

No. A dog's first year is about 15 human years and the second about 9 more. After that each year is roughly 4 for small dogs, 4 to 5 for medium dogs, 5 to 6 for large dogs and about 7 for giant breeds, so a 10-year-old large dog is about 66, not 70.

How old is a 10-year-old cat in human years?

A 10-year-old cat is about 56 in human years, at the end of the mature adult stage. Cats over 10 are classed as seniors, and a 15-year-old cat is about 76.

What size dog can I keep in an HDB flat?

HDB allows one dog per flat, from the AVS list of approved small breeds (or a cross of two approved breeds), and most of those fall in the small band of this chart. AVS's Project ADORE also lets some larger mixed-breed dogs be adopted into HDB flats.

Dog age	Small	Medium	Large	Giant
1	15	15	15	12
2	24	24	24	22
3	28	28	28	31
4	32	32	32	38
5	36	36	36	45
6	40	42	45	49
7	44	47	50	56
8	48	51	55	64
9	52	56	61	71
10	56	60	66	79
11	60	65	72	86
12	64	69	77	93
13	68	74	82	100
14	72	78	88	107
15	76	83	93	114
16	80	87	99	121

Dog age	Small	Medium	Large	Giant
1	15	15	15	12
2	24	24	24	22
3	28	28	28	31
4	32	32	32	38
5	36	36	36	45
6	40	42	45	49
7	44	47	50	56
8	48	51	55	64
9	52	56	61	71
10	56	60	66	79
11	60	65	72	86
12	64	69	77	93
13	68	74	82	100
14	72	78	88	107
15	76	83	93	114
16	80	87	99	121