Dog Years to Human Years: Chart by Size

By the PawMathCalc Team · Updated October 26, 2026

Short answer: the first dog year equals about 15 human years and the second about 9 more (24 in total). After that, small dogs add about 4 human years per year, medium dogs about 5, large dogs about 6 and giant breeds about 7. A 10-year-old dog is 56 to 79 in human years depending on size.

Dog age chart

Dog age	Small (up to 20 lb)	Medium (21-50 lb)	Large (51-100 lb)	Giant (over 100 lb)	DNA formula
1	15	15	15	12	31
2	24	24	24	22	42
3	28	28	28	31	49
4	32	32	32	38	53
5	36	36	36	45	57
6	40	42	45	49	60
7	44	47	50	56	62
8	48	51	55	64	64
9	52	56	61	71	66
10	56	60	66	79	68
11	60	65	72	86	69
12	64	69	77	93	71
13	68	74	82	100	72
14	72	78	88	107	73
15	76	83	93	114	74
16	80	87	99	121	75

Why the 7 year rule is wrong

Multiplying by 7 makes a 1-year-old dog a 7-year-old child, but at one year most dogs are fully grown and can have puppies, more like a teenager. And it treats a Chihuahua and a Great Dane the same, although giant breeds age much faster and usually live several years less.

The DNA formula

Human age = 16 × ln(dog age) + 31

Researchers at UC San Diego (Wang et al., Cell Systems, 2020) compared age-related DNA changes in Labrador Retrievers and people. Their formula says dogs age very fast early on (a 2-year-old Lab is like a 42-year-old) and slowly later. It was built from one breed, so the size chart is better for comparing different dogs.

When is my dog a senior?

Size	Usually senior from
Small	about 10-11 years
Medium	about 9 years
Large	about 8 years
Giant	about 6-7 years

These are the ages where the chart passes about 56 human years. Seniors do best with checkups twice a year, blood tests, weight control and dental care.

Sources: AVMA style dog age chart by size; Wang T. et al., Cell Systems (2020).

Try the dog age calculator

Enter your own numbers below, or open the full dog age calculator with the formula and more examples.

This guide is general information, not veterinary advice. Your pet may differ: ask your vet. Terms

Frequently asked questions

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

About 36 for small, medium and large dogs, and about 45 for a giant breed.

How old is a 10 year old dog in human years?

About 56 for a small dog, 60 for a medium dog, 66 for a large dog and 79 for a giant breed.

Is 1 dog year 7 human years?

No. The first year is about 15 human years and the second about 9 more; after that it depends on the dog's size.

How old is a 15 year old dog in human years?

About 76 for a small dog and 83 for a medium dog. Few large and giant dogs reach 15.

More guides

How Long Do Dogs Live?

Dog age	Small (up to 20 lb)	Medium (21-50 lb)	Large (51-100 lb)	Giant (over 100 lb)	DNA formula
1	15	15	15	12	31
2	24	24	24	22	42
3	28	28	28	31	49
4	32	32	32	38	53
5	36	36	36	45	57
6	40	42	45	49	60
7	44	47	50	56	62
8	48	51	55	64	64
9	52	56	61	71	66
10	56	60	66	79	68
11	60	65	72	86	69
12	64	69	77	93	71
13	68	74	82	100	72
14	72	78	88	107	73
15	76	83	93	114	74
16	80	87	99	121	75

Dog age	Small (up to 20 lb)	Medium (21-50 lb)	Large (51-100 lb)	Giant (over 100 lb)	DNA formula
1	15	15	15	12	31
2	24	24	24	22	42
3	28	28	28	31	49
4	32	32	32	38	53
5	36	36	36	45	57
6	40	42	45	49	60
7	44	47	50	56	62
8	48	51	55	64	64
9	52	56	61	71	66
10	56	60	66	79	68
11	60	65	72	86	69
12	64	69	77	93	71
13	68	74	82	100	72
14	72	78	88	107	73
15	76	83	93	114	74
16	80	87	99	121	75

Dog age	Small (up to 20 lb)	Medium (21-50 lb)	Large (51-100 lb)	Giant (over 100 lb)	DNA formula
1	15	15	15	12	31
2	24	24	24	22	42
3	28	28	28	31	49
4	32	32	32	38	53
5	36	36	36	45	57
6	40	42	45	49	60
7	44	47	50	56	62
8	48	51	55	64	64
9	52	56	61	71	66
10	56	60	66	79	68
11	60	65	72	86	69
12	64	69	77	93	71
13	68	74	82	100	72
14	72	78	88	107	73
15	76	83	93	114	74
16	80	87	99	121	75