A puppy's first year counts for 15-20 human years depending on breed size.
Puppy
For the next few years as a "youth", each dog year equals 4-5 human years.
Youth
In adulthood, every year translates to 4-6 human years, based on if dog is small, medium or big.
Adulthood
At age 7+, dogs enter "senior" status. Factor breed lifespan to calculate age.
Senior
Small dogs' lifespan is longer so their first 2 years equal 14 human years.
Small Breeds
Medium dogs age a bit faster. Their first 2 years equals 16 human years.
Medium Breeds
Large breeds have shortest lifespans, so their first 2 years is 18 human years.
Large Breeds