All Health Calculators
35 free calculators and reference tools in 5 categories. Every tool uses NHANES data, a peer-reviewed normative study, or published fitness standards. Private, no signup, all calculations happen in your browser.
Not sure where to start?
These three are the highest-impact measurements — each validated by decades of research.
Grip strength predicts mortality better than blood pressure in some studies. If you only measure one thing, measure this.
Open calculator → Best for weight Waist CircumferenceBelly fat is metabolically active and drives diabetes and heart disease risk. More useful than the scale for tracking progress.
Open calculator → Best for cardio Resting Heart RateLower is consistently better for longevity. Tracks your aerobic fitness and responds quickly to exercise — see results in weeks.
Open calculator →Strength & Upper Body
Grip strength, lean body mass, arm circumference, and strength-to-weight ratios.
Body Girth & Adiposity
Waist, hip, WHR, and BMI. The measurements clinicians use most for cardiometabolic screening.
Vital Signs & Cardiac
Resting heart rate, walking speed, and gait speed norms. Strong markers of cardiovascular fitness.
Body Shape Indices
Body Roundness Index and Waist-to-Height Ratio. Newer metrics that model fat distribution.
Fitness Tests & Standards
Push-up, sit-and-reach, vertical jump, strength standards, and functional mobility tests.
Why percentile calculators matter
Most health tools tell you whether your value falls inside a fixed range — under 25 BMI, under 94 cm waist, under 100 bpm heart rate. That approach is easy but misleading. A BMI of 27 at age 25 means something very different than a BMI of 27 at age 65, because the population distribution shifts with age. A grip strength of 35 kg is excellent for a 70-year-old woman and below average for a 30-year-old man.
Percentile calculators solve this by comparing you to age- and sex-matched peers from the same population. Instead of a category, you get a rank: where exactly do you fall among thousands of US adults who look like you? This makes the result interpretable in a way fixed cutoffs cannot match.
Health measurement tools use one of two reference sources. NHANES 2011-2023 (the CDC's continuous health and nutrition examination survey, n ≈ 47,000) covers body measures, grip strength, resting heart rate, and gait speed. Peer-reviewed meta-analyses (Bohannon for walking speed, Boer for lean body mass, ACSM for strength ratios) fill in the gaps where NHANES does not measure the variable directly. Every threshold, percentile, and cutoff traces back to a published study — no invented categories.
The Fitness Tests & Standards category works the same way but for performance metrics: push-up and curl-up tests use FitnessGram healthy fitness zones (The Cooper Institute), strength standards use published Strength Level / ExRx tables, the beep test uses the Léger regression for VO2max, and the functional mobility tests (TUG, sit-to-stand, functional reach) use the clinical cutoffs from the original published studies. You enter your result and get a rating against the relevant reference population.
Pick the measurement most relevant to your health goal, or start with the foundational ones: grip strength (overall strength and longevity marker), waist circumference (cardiometabolic risk), and resting heart rate (cardiorespiratory fitness).