Dog Age Calculator

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

100

107

114

121

Convert a dog's chronological age to a human-age estimate using an adult-size chart. Enter years and months or use an exact birth date, compare the published UCSD epigenetic formula, and see the complete age chart for four size groups.

How to use this calculator

Enter the dog’s age and the size category requested by the form. Treat the converted age as a comparison between life stages, not a precise biological age. Dogs of the same age can have different health and activity needs.

Examples

10-year-old large dog

The size chart estimates 66 human years. The UCSD comparison is about 67.8 years, while the old 7:1 shortcut says 70.

Six-year-old medium dog

The size-aware result is 42 human years and the life-stage estimate is mature adult.

Formula

The size-aware chart gives the primary headline estimate. Between whole years, the calculator interpolates between adjacent chart values. Beyond the chart it continues at the most recent size-specific aging rate.

The UCSD research comparison is:

human age = 16 × ln(dog age) + 31

The traditional comparison is simply dog age × 7, but that shortcut is not biologically representative.

These estimates describe population patterns, not an individual dog's health or remaining lifespan. Size, breed, genetics, weight, and medical history all matter.

Evidence and interpretation limits

The size table is an age-comparison model, not a biological clock. The logarithmic methylation relationship came from a Labrador retriever study and should not be generalized into an individual prognosis. Breed, adult weight, disease, and veterinary history matter more than a human-age label. Use the size-aware figure as the primary comparison and discuss life-stage care with a veterinarian.

Frequently asked questions

How old is my dog in human years?

Dogs mature much faster in their first two years and then age at rates that vary with adult size. A medium dog is roughly 15 human years at one, 24 at two, and about 60 at ten. Larger dogs generally age faster later.

Is one dog year equal to seven human years?

No. The 7-to-1 rule ignores rapid early development and size differences. It is included only as a familiar comparison, not the primary result.

What is the UCSD dog-age formula?

Researchers comparing DNA methylation in Labrador retrievers and humans published human age = 16 × ln(dog age) + 31. It is an epigenetic comparison from one breed, so it is not a universal veterinary clock.

Does breed size affect dog aging?

Yes. Small dogs tend to live longer and become seniors later than large and giant dogs. The size-aware chart separates small, medium, large, and giant adult weight groups.

Is this veterinary advice?

No. Human-equivalent ages and life stages are estimates. A veterinarian should assess your dog's health, breed risks, and individual needs.

Compare scenarios

How to use this calculator

Examples

Formula

Evidence and interpretation limits

Frequently asked questions

Related calculators

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

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