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 ads. The page is the calculator. We use lightweight, privacy-conscious analytics (Google Analytics and Ahrefs) to understand aggregate usage — never to target you or sell your data.
- 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.