About ProHealthCalc
Our Mission
ProHealthCalc collects the calculators you would otherwise hunt for across a dozen sites — BMI, TDEE, due date, GFR, A1C, PHQ-9 and the rest — and puts them in one place, free, with the formula and the source named on every page. The point is to let you reach a number quickly and understand where it came from, without an account and without your inputs leaving your browser.
Background
Most health calculators on the open web fall into one of three buckets: they use the wrong formula, they hide the math behind a paywall, or they give you a number with no context for when it applies and when it doesn't. ProHealthCalc was built to do the boring opposite: pick the formula the relevant authority (WHO, CDC, NIH, AHA, or a peer-reviewed study) actually uses, implement it carefully, and show that source on the page. The library currently covers around 70 calculators across body composition, nutrition, fitness, pregnancy, women's and men's health, mental health, sleep, diabetes, cardiology and pediatrics.
How accuracy is handled
Each calculator references a specific guideline or study — WHO BMI cut-offs, the CDC growth charts, the Cockcroft-Gault and CKD-EPI equations for kidney function, the Mifflin-St Jeor equation for resting metabolic rate, the FINDRISC questionnaire for diabetes risk, and so on. The reference list at the bottom of each page is the actual source the math came from, not a vague 'reviewed by experts' line. If a guideline is updated, the calculator follows.
How a calculator is built
For each calculator: pick the formula the field actually uses (the one cited in the WHO/NIH/relevant society guideline, or the most-cited peer-reviewed paper). Implement it with attention to unit conversions and edge cases. Write the page so you can read the formula in plain language, see a worked example, see when it doesn't apply, and check the source. Inputs never leave your browser, which is also why no input history is shown — there's nothing stored to show.
What the site does not claim
ProHealthCalc is not a clinic, the calculators are not a diagnosis, and there is no doctor on call reviewing your individual numbers. The site provides the math and the context; interpretation for your situation is a job for a clinician who knows your history. Every calculator page repeats this in its disclaimer, and any result that crosses a clinically meaningful threshold links you to authoritative resources rather than offering medical advice.
What's actually different
Every formula has a named source — WHO, CDC, NIH, AHA, or the original peer-reviewed study, listed at the bottom of the page
Inputs never leave your browser — no account, no analytics on what you type, no third party can see your numbers
No paid tier, no email gate, no 'unlock the full result for $5' — the whole site is the same for everyone
Works on the phone you already have, no install, no permissions, page loads in well under a second
Each calculator includes the formula in plain language, a worked example, the known limitations, and when not to trust the result
When a guideline changes (e.g. updated WHO BMI cut-offs), the calculator and its references are updated