About thehealthcalc.co

What we do

thehealthcalc.co is a small set of free, anonymous health calculators. Pick a measurement, enter your age and sex, and the tool tells you how your number compares to the US population using percentile distributions from the CDC's National Health and Nutrition Examination Survey (NHANES) and other peer-reviewed normative studies.

Every calculation runs in your browser. We do not store the values you enter, we do not require an account, and we do not sell data — because we never collect it in the first place.

Why we built it

Most online health calculators give you a single number with no context. A BMI of 26.4 alone tells you almost nothing — is that high for a 50-year-old man, normal for a 25-year-old woman, or a sign of athletic muscle mass? Percentile rankings answer the question most people are actually asking: "Compared to other people like me, how am I doing?"

So we built the calculators we wished existed: research-grade data, clear methodology, no signup, no clutter.

Our data

All tools use one of two primary sources:

• NHANES 2011–2023 — the CDC's continuous health survey covering roughly 56,000 US adults across five 2-year cycles (G, H, I, J, L; the 2019-2020 K cycle was suspended due to COVID-19). NHANES combines interviews, physical exams, and lab tests, and is the gold-standard source for population-representative US health data. Grip strength is limited to 2011–2014 (discontinued after that cycle).
• Published normative studies — for metrics NHANES does not capture directly, we use peer-reviewed meta-analyses (e.g., Bohannon 2008 for gait speed) with citation on every tool page.

Every tool page links to the exact dataset, sample size, and the published threshold studies it relies on. We do not invent cutoffs or paraphrase secondary sources.

Who we are

thehealthcalc.co is built and maintained by a small independent team. We are not a hospital, a clinic, or a government agency — we are a consumer health-data project that believes good population-health numbers should be free, transparent, and easy to use.

Our editorial policy describes how we pick which metrics to publish, how the data is sourced and updated, and the limits of what these calculators can and cannot tell you.

What thehealthcalc.co is not

We are a screening and education tool, not a diagnostic service. Our calculators:

• Are not a substitute for medical advice from a licensed clinician.
• Do not provide diagnoses, treatment plans, or prescriptions.
• Are based on population averages — your individual health depends on many factors these tools cannot measure.

If a result concerns you, talk to a doctor. We say this on every page and we mean it.

How we stay free

The site is supported by non-personalized advertising (Google AdSense) and our own time. We do not run sponsored content, we do not sell user data (we have none), and we do not accept payment to rank any measurement higher than another.