Dog & cat age charts

Dog age chart

Dog age	Small (≤20 kg)	Medium (21–50 kg)	Large (>50 kg)	Life stage
1 month	2.5 years	2.5 years	2.5 years	Puppy
2 months	5 years	5 years	5 years	Puppy
3 months	7.5 years	7.5 years	7.5 years	Puppy
4 months	10 years	10 years	10 years	Puppy
5 months	12.5 years	12.5 years	12.5 years	Puppy
6 months	15 years	15 years	15 years	Puppy
7 months	16.5 years	16.5 years	16.5 years	Puppy
8 months	18 years	18 years	18 years	Puppy
9 months	19.5 years	19.5 years	19.5 years	Puppy
10 months	21 years	21 years	21 years	Puppy
11 months	22.5 years	22.5 years	22.5 years	Puppy
1 year	24 years	24 years	24 years	Young adult
2 years	24 years	24 years	24 years	Adult
3 years	28 years	29 years	30 years	Adult
4 years	32 years	34 years	36 years	Adult
5 years	36 years	39 years	42 years	Adult
6 years	40 years	44 years	48 years	Middle age
7 years	44 years	49 years	54 years	Middle age
8 years	48 years	54 years	60 years	Middle age
9 years	52 years	59 years	66 years	Senior
10 years	56 years	64 years	72 years	Senior
11 years	61 years	70 years	80 years	Senior
12 years	66 years	76 years	88 years	Senior
13 years	71 years	83 years	96 years	Geriatric
14 years	76 years	90 years	104 years	Geriatric
15 years	81 years	97 years	112 years	Geriatric
16 years	88 years	105 years	121 years	Geriatric
17 years	95 years	113 years	130 years	Geriatric
18 years	102 years	121 years	139 years	Geriatric
19 years	109 years	129 years	148 years	Geriatric
20 years	116 years	137 years	157 years	Geriatric

Cat age chart

Cat age	Human years	Life stage	What to expect
1 month	2.5 years	Kitten	Just weaned; learning independence
2 months	5 years	Kitten	Vaccine visits; early socialization
3 months	7.5 years	Kitten	Growing fast; personality forming
4 months	10 years	Kitten	Teething — chew toys help
5 months	12.5 years	Kitten	Sexual maturity may begin; ask your vet about spay/neuter
6 months	15 years	Kitten	Nearly mature, still filling out
7 months	16.5 years	Kitten	Body nearly adult-ready
8 months	18 years	Kitten	Personality settling; more adult behavior
9 months	19.5 years	Kitten	Sexually mature; discuss spay/neuter with your vet
10 months	21 years	Kitten	Physical growth mostly complete
11 months	22.5 years	Kitten	Near adult; steadier habits
1 year	24 years	Young adult	Sexually mature; body still finishing up
2 years	24 years	Adult	Fully mature and energetic
3 years	28 years	Adult	Personality settling; more adult behavior
4 years	32 years	Adult	Often peak fitness
5 years	36 years	Adult	Early aging signs may appear
6 years	40 years	Middle age	Worth a closer eye on health
7 years	44 years	Middle age	Consider checkups more often
8 years	48 years	Middle age	Health issues become more common
9 years	52 years	Senior	Extra care often helps
10 years	56 years	Senior	Senior years — watch for changes
11 years	61 years	Senior	More frequent checkups help
12 years	66 years	Senior	Cognitive changes can appear
13 years	71 years	Geriatric	Geriatric care recommended
14 years	76 years	Geriatric	Frequent checkups; watch closely
15 years	81 years	Geriatric	May need closer day-to-day care
16 years	88 years	Geriatric	A rare senior — celebrate carefully
17 years	95 years	Geriatric	Rare age; stay close with your vet
18 years	102 years	Geriatric	Rare senior years
19 years	109 years	Geriatric	Rare age; may need round-the-clock support
20 years	116 years	Geriatric	Rare age; work closely with your vet

Size, lifespan & aging

Small dogs

🐕

Typical lifespan: 12–18 years

Aging pattern: Mature early, often age more slowly later

Examples: Chihuahua, Pomeranian, Yorkshire Terrier

Medium dogs

🐕

Typical lifespan: 10–15 years

Aging pattern: Middle of the pack for growth and longevity

Examples: Golden Retriever, Labrador, Border Collie

Large dogs

🐕

Typical lifespan: 8–13 years

Aging pattern: Grow for longer, then often age faster

Examples: German Shepherd, Husky, Great Dane

Cats

🐱

Typical lifespan: 12–20 years

Aging pattern: Indoor cats often live longer

Also matters: Breed, environment, and everyday care

Care tips by life stage

Puppy / kitten (0–1 year)

Stay on your vet’s vaccine schedule
Start gentle training and house manners
Feed food made for puppies or kittens
Offer play that builds coordination safely
Socialize early with people and calm pets
Keep up with deworming as advised

Young adult (1–2 years)

Finish the core vaccine series
Keep training consistent
Support growth with balanced nutrition
Build a steady daily routine
Catch problem behaviors early
Schedule regular wellness checkups

Adult (about 3–7 years)

Match exercise to their energy — avoid weight creep
Plan 1–2 vet visits a year
Brush teeth or use dental chews your vet likes
Keep meals balanced; watch treats
Offer puzzles or training for mental work
Make time for company every day

Middle age (about 8–12 years)

Consider checkups every 6 months
Ask about food formulas for older pets
Protect joints — skip hard jumping
Keep minds busy with gentle enrichment
Watch temperature; seniors chill easily
Check teeth and gums regularly

Senior (about 12–16 years)

Keep a 6-month checkup rhythm
Switch to senior-friendly food if recommended
Make resting spots warm and easy to reach
Spend quieter quality time together
Note confusion, pacing, or sleep changes
Ask your vet about joint support

Geriatric (16+ years)

Check in with your vet more often
Use nutrition plans built for very senior pets
Keep the home calm, warm, and predictable
Watch cognition and appetite closely
Soft beds help stiff joints
Keep routines simple and familiar

Why not just multiply by 7?

The “1 pet year = 7 human years” shortcut ignores how uneven aging really is. A better mental model:

Year one is huge: The first months pack in a lot of growth — closer to toddler-to-teen leaps than a steady ×7
Young adulthood still moves fast: Years 1–2 often map to late teens / early twenties
Adulthood levels out: Mid years add human years more slowly than puppyhood did
Middle age needs attention: From roughly year 8 onward, health checks matter more
Senior years accelerate: Later life often maps to bigger human-year jumps, especially in large dogs

The first year, in plain terms

Early life looks a lot like human infancy and childhood sped up:

Fast growth: Bodies change quickly and need the right calories
Immunity building: Vaccines protect while systems mature
Learning: House manners and social skills stick best early
Personality: Calm, consistent training shapes lifelong habits

How PetAge estimates age

What we draw on

Our calculator follows common veterinary-style conversion patterns used in pet education materials:

Life-stage curves: Early years count for more human years than later ones
Size bands for dogs: Small, medium, and large dogs use different curves
Published charts: Aligns with widely shared dog/cat age tables owners already see at clinics
Honest limits: It’s an estimate for education — not a medical test

Under one year

Because puppies and kittens change quickly, we break the first year into finer steps:

0–6 months: Faster mapping (about 2.5 human years per month in our chart)
6–12 months: Slower mapping (about 1.5 human years per month)
Why: It mirrors the burst-then-settle growth pattern most owners see

Design choices

Non-linear: Not a flat multiply-by-seven
Segmented: Different bands across the lifespan
Dog size aware: Optional size input improves dog estimates
0–20 years: Covers typical and very senior pets
Month-level early on: Finer detail while they’re still growing

Try the calculator when you’re ready for a personalized estimate.