Calculate SimplyHow to use
Start with the worked example to understand the inputs, then replace every relevant value with your own figures. Use one currency and consistent units throughout. Add or remove rows where offered; irrelevant conditional fields are disabled and excluded. Select Calculate after editing. Review negative values and any “not determined” result rather than assuming every scenario must be profitable. Download a text summary or print the page for your records.
Formula and assumptions
This is an educational age comparison, not a biological clock or veterinary assessment. The general medium-dog convention uses approximately 15 human years at one calendar year, 24 at two, then five more per year. The cat convention adds four per year after two. Partial years are interpolated. Dog breed-size differences are not modeled in that human-age number. Dog senior stage begins at 75% of the lifespan you enter; cat life stages follow AAHA age bands. Individual development and health can differ considerably.
rough medium-dog guideline: year 1 ≈ 15; year 2 ≈ 24; subsequent year +5. Cat convention: subsequent year +4. Partial years are linearly interpolated.
Worked example
Example only: replace rates with your own figures.
Inputs
- Pet species: dog
- Age in completed years: 5
- Additional months: 0
- Expected breed lifespan for dog life-stage estimate: 12
- Calendar pet age: 5 years
- Approximate human-age equivalent: 39 years
- Life stage: Mature adult
Frequently asked questions
Are the example rates current market prices?
No. Example inputs demonstrate arithmetic, not live prices, tax rules, salary surveys or sponsor benchmarks. Enter a dated quote, bill, manufacturer specification or verified fee schedule that applies to your situation. Compare a conservative and an optimistic scenario separately.
Why is a result not determined?
Some calculations have no meaningful value when a denominator is zero, savings are non-positive, a target cannot be reached or your data do not bracket an intersection. The tool leaves that result undetermined instead of displaying infinity or inventing a recommendation. Check the method and your inputs.
Sources
Sources explain the underlying concepts, not an endorsement of this website or its results. Method review: 20 October 2026.