Puppy Age Calculator
Enter your puppy's birth date to calculate their exact age in days, weeks, and months — plus their current development stage, what milestones to expect right now, and what's coming next.
Useful for breeders tracking litter development, new owners understanding their puppy's behaviour, or anyone with an estimated date of birth from a rescue.
Have a litter on the way? Calculate your whelping date first, then come back here once they've arrived.
Understanding puppy development stages
- The socialisation window (4–8 weeks) is the most important period for lifelong temperament
- The fear imprint period (8–10 weeks) means negative experiences hit harder than at any other age
- Adolescence (4–12 months) is when most owners think training has failed — it hasn't
Why development stages matter for breeders
Understanding what's happening neurologically at each stage helps breeders make better decisions — when to introduce enrichment, when to send puppies home, how to prepare buyers for what's ahead. A breeder who sends a puppy home at 6 weeks versus 8 weeks is sending a fundamentally different animal in terms of emotional development.
The adolescent phase — what to tell buyers
The single most common reason dogs are surrendered to shelters is adolescent behaviour between 6 and 18 months. Dogs that seemed perfectly trained suddenly ignore commands, test boundaries, and become destructive or reactive. This is normal neurological development, not a failed dog. Breeders who educate buyers about this phase before they experience it get far fewer return requests.
Puppy development essentials
Tools that support healthy development at every stage.
Digital Thermometer
Monitor newborn puppy temperatures during the neonatal stage.
View on Amazon →
Complete Whelping Kit
Everything you need for the first weeks with a new litter.
View on Amazon →
Breeder Record Book
Track developmental milestones and litter notes in one place.
View on Amazon →
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Puppy age & development FAQs
How do I calculate my puppy's age in weeks?
Enter your puppy's birth date and the calculator works out their exact age in days, weeks, and months automatically. Weeks are the most useful unit for tracking puppy development in the early months.
What are the key puppy development stages?
Puppies go through several distinct stages: Neonatal (0–2 weeks), Transitional (2–4 weeks), Socialisation (4–8 weeks), Fear Imprint Period (8–12 weeks), Juvenile (12–16 weeks), and Adolescent (4–12 months). Each stage has different needs and learning windows.
When do puppies open their eyes?
Puppies typically open their eyes between day 10 and day 14. Their ear canals open slightly later, around day 18. Both senses are functional but not fully developed at this point — full visual acuity takes several more weeks.
When is a puppy ready to go to a new home?
8 weeks is the widely accepted minimum age for rehoming. This allows puppies to complete key socialisation with their dam and littermates. Some breeders prefer to wait until 9 or 10 weeks, especially for smaller or more sensitive breeds. Going home earlier than 8 weeks is associated with increased behavioural issues.
When do puppies go through fear periods?
The most significant fear imprint period occurs around 8–10 weeks of age. A second fear period often occurs during adolescence, typically around 6–14 months depending on the breed. During these windows, frightening experiences can have a disproportionate and lasting impact.
At what age are dogs fully mature?
It depends on size. Small breeds reach full physical maturity around 10–12 months. Medium breeds around 12–15 months. Large breeds 18–24 months. Giant breeds can continue maturing physically until 2–3 years old. Mental maturity generally lags physical maturity by several months.