Dog age calculator
A dog age in its own years is the same calendar arithmetic as a person. The human-equivalent conversion is a separate step and depends heavily on size; a Great Dane at seven is elderly while a Chihuahua is middle-aged.
How to work out a dog age
Rescue dogs rarely come with a date of birth, and the estimate usually comes from teeth. Puppies have a predictable dental timeline that gives an age to within weeks up to about seven months; after that, wear and tartar give only a rough band, and a vet estimate of "three to five years" is genuinely as precise as it gets. Recording an approximate birth date and sticking to it is more useful than re-estimating.
Questions
From its date of birth, the same as any age. Converting to human years is a separate step.
A vet can estimate from teeth: accurately for puppies, only roughly for adults.
Small breeds by about a year, large breeds nearer eighteen months to two years.
It varies by age and size. The first year is about fifteen, the second nine, then four to seven.
Around seven for large breeds, ten or later for small ones.