It's the age-old question, how
old is my dog in human years? Many factors contribute to answering
this question. A dog's breed, health, nutrition, and weight are
certainly contributing factors.
Dog Age
Calculator #1
(slide the
triangle button across the sliding scale
until you reach the number of human years
you believe your dog to be -
the dog years will appear below on the graph)
Dog Age Calculator #2
(based upon weight added in)
Calculate a dog's age in human years
by
using the dog's age and weight.
This dog age calculator determines a dog's age by factoring in the
weight of the dog. Small dogs typically live longer lives than heavy
dogs making the standard ('human age' = 'dog age' x 7) equation
inaccurate.
This dog age calculation is based on a chart developed by Fred L.
Metzger, DVM. William Fortney, DVM, R.T. Goldston, DVM and Ernest Ward
Jr., DVM adapted the chart. Griscotti's was able to develop an
equation that would closely resemble the original chart. Some
assumptions were made, the original data contained weight ranges. The
mean of these ranges was used as the actual weight reflecting the
dog's human age. For example, the chart indicates that a 10-year-old
dog that weighs between 21 and 50 pounds is approximately 56 in human
years. In order to form an equation, an exact weight had to be
extracted. The mean was used as the exact weight, yielding that a dog
weighing 35 pounds is approximately 56 years old in human years. This
conversion was performed for each listed weight range below 91 pounds.
The ranges described in the chart are the following: 20lbs small dogs,
21-50lbs medium dogs, 51-90lbs large dogs. Dogs greater than 90 lbs
are considered to be giant dogs. The calculated equation is optimized
for weights below 90 lbs, though it can be used on weights above 90
lbs. No specific weight could be extracted from the chart for dogs
weighing more than 90 lbs, so accuracy above 90 lbs is unknown.
The equation developed is parabolic in nature for determining the dogs
age increment per year. The equation matches the reported human age
found in the chart by +/- 1.16 percent at all weights up to 90 pounds.
A best-fit analysis was performed to find an equation that given a
weight and dog age, the result will closely match the reported chart
data. The equation is used on dogs' ages 3 and up. For dogs under 3
years old, the equation is used to calculate the human age of a 3 year
old dog at the given dog weight. A parabola is projected though this
point (human age) giving a focal length. The focal length is used with
the given dog age to find a corresponding human age. Again, this is
done at dog age 3 and under only. The rational behind using a
parabolic equation is that it provides a nice age curve showing that
dogs mature rather quickly in the early years, then once mature, the
amount of human years per dog years is constant.
The equations used are approximations of dog age. They seem to be
better than the 7x equation. Give the calculator a try! We would love
to improve the equation, send us any data or insight on the subject.
(calculator@griscotti.com)