Methodology
How we build each calculator
The process is the same for every calculator on the site. We pick a single question, write the formula in plain text, build the inputs around it, and stop.
Show the math
Every calculator has a How it works section with the actual formula. If we can't explain it in a few lines, we don't ship it.
Use modern formulas
Where research has improved on a folk rule, we use the better formula and explain why. The dog age calculator uses the 2019 logarithmic model from Wang et al., not the “dog years × 7” rule of thumb.
Update as you type
Results change live as inputs change. No “Calculate” button, no spinner. The page that loads is the calculator.
What we don't do
- No fake calculators. If a calculator isn't built and tested, it isn't in the menu.
- No medical or legal advice. Calculators that touch health (pet age) or money (sales tax, tip) are informational. For decisions that matter, talk to a professional.
Analytics
We use Google Analytics and Ahrefs Analytics to understand how the site is used and which calculators need work. Calculator inputs are computed in your browser and are not sent to either tool. See the privacy policy for what these tools collect.