About Smart Calculators
We build free calculators for the numbers that matter — what you eat, how you train, how your money grows. Every tool is paired with a written guide that shows the formula, the assumptions, and the edge cases, so you can trust the output or reproduce it by hand.
Our approach
The internet is full of calculators that return a number and tell you nothing about where it came from. That is not useful and, in health and finance, it is sometimes harmful. Every calculator on this site is paired with the underlying formula, the source it comes from, the population it applies to, and the ±% error you should expect.
We do not sell courses, supplements, financial products, or newsletters. The site is funded entirely by display advertising. That keeps the editorial line clean: we have no incentive to recommend the product with the biggest affiliate payout, because there is no affiliate payout.
How we write
Every guide starts with a quick answer, because most people want the number first. It is followed by the formula, a worked example, the caveats, and an FAQ. We read the primary literature where we can and link to it where it helps. We do not pretend to be doctors, dietitians, or financial advisors — when a topic crosses that line, we say so and point you to a professional.
Editors
Elena has spent the last decade translating research in exercise physiology and nutrition into practical advice for people who train. Her work focuses on cutting through hype — what the evidence actually supports, where popular claims fall apart, and how to use numbers like TDEE, BMI, and heart-rate zones without overfitting them. She reads the primary literature so readers don't have to, and writes every article with the goal that someone can finish it and know exactly what to do next.
Jonah covers the math of money — compound interest, savings goals, inflation, and the small number of decisions that actually move the needle on long-term wealth. His background is in financial analysis, and he approaches personal-finance writing the same way: with worked examples, explicit assumptions, and a strong preference for showing his work. He does not sell courses, recommend stocks, or run an investment newsletter.
Contact
Corrections, questions, or suggestions for new calculators: [email protected].