Dog age calculator
A dog’s age from its date of birth in years, months and weeks. Weeks are the unit that matters for the first half-year: the socialisation window, the vaccination course and the earliest lawful rehoming age are all written in weeks, and each of them closes.
How to work out a dog age
Development in the first year runs to a schedule tight enough that a week either way changes the advice, which is why breeders and vets talk in weeks rather than months. Deciduous teeth arrive from about three weeks and the full set of twenty-eight is in by six to eight. Eight weeks is the earliest a puppy may lawfully be sold in England, and the breeder has to hand it over in person. The socialisation window — when a puppy meets new people, surfaces and noises without learning to fear them — runs from roughly three weeks to fourteen and then narrows; what is missed in it takes far more work to teach afterwards. The core vaccination course starts around six to eight weeks and finishes near sixteen, and the puppy is not covered until a fortnight after the final dose.
The permanent teeth are what let a vet put an age on a dog nobody has papers for. All forty-two are through by about seven months, and up to that point the eruption order gives an estimate accurate to a fortnight or so. Past it the evidence is wear and tartar, which vary with diet and chewing habit more than with age, so "three to five years" is genuinely as precise as the method gets.
Growth plates are the other date worth knowing, because it governs exercise rather than paperwork. They close at about ten to twelve months in small breeds and fourteen to eighteen in large and giant ones, and repeated high-impact work before that point — long road runs, stairs, jumping down out of a car — is what the orthopaedic advice is aimed at.
What people use it for
- Checking a puppy is old enough to leave its litter
- Timing the vaccination course by week rather than by month
- Knowing whether the socialisation window is still open
- Working out when a large breed can start proper road walks
- Putting a working birth date on a rescue with no paperwork
Questions
From its date of birth. Under six months, read the answer in weeks: that is the unit every developmental milestone is written in.
Eight weeks at the earliest, and in England the breeder is required to hand the puppy over in person.
From about three months, with all forty-two permanent teeth through by around seven.
Roughly three to fourteen weeks. Things met inside it are accepted; the same things introduced later take much more work.
Ten to twelve months in small breeds, fourteen to eighteen in large and giant ones. Keep the high-impact exercise down until then.
To within a fortnight up to seven months, from the teeth coming through. After that it is wear and tartar, which give a band of a few years at best.