Dog Age Calculator

Enter your dog's age in years and months, or pick a birthday, and choose a size. DogAgeCalc converts the age to human years using the size-based chart vets use, shows the newer DNA-based estimate and the old 7-year rule side by side, and tells you which life stage your dog is in.

Small dogs age slowly after the first two years and big dogs age faster, which is why a single multiplier never fits. Switch to Cat for the feline version.

Dog age chart

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

How the dog age calculator works

DogAgeCalc looks up your dog's age in the size-based chart above and interpolates between whole years, so 2 years and 6 months sits halfway between the year-two and year-three values. Past 16, it keeps adding the last yearly step for that size. Months under a year are spread evenly across the first year.

The DNA-based figure comes from a 2020 study of Labrador retrievers that compared chemical changes in DNA with those in people. It suggests human age ≈ 16 × ln(dog age) + 31, which makes young dogs much "older" than the chart: a 1 year old comes out at 31. It was measured in a single breed, so treat it as an interesting comparison rather than a rule.

Life stages

Dogs are puppies until about one year (18 months for giant breeds), young adults until three, and mature adults until the last quarter of their expected lifespan, when they become seniors. Typical lifespans used here are 15 years for small dogs, 13 for medium, 11 for large and 9 for giant breeds. Individual dogs vary a lot, so your vet's view always wins. Everything is calculated in your browser.

Frequently asked questions

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

About 36 for small and medium dogs, and 36–45 for large and giant breeds.

Is one dog year really 7 human years?

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

Which size should I choose for a mixed breed?

Pick the group that matches the adult weight.

Is DogAgeCalc free?

Yes, with no sign-up or ads.

Is my pet's age saved?

Yes, in this browser only.

Dog age chart

How the dog age calculator works

Life stages

Frequently asked questions

More tools

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

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

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