All Health Calculators

13 free percentile calculators in 4 categories. Every tool uses NHANES data or a peer-reviewed normative study. 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.

Best all-around 💪 Grip Strength

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 Circumference

Belly 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 Rate

Lower 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.

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Grip Strength How your hand strength compares to US adults your age. A powerful longevity predictor.
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Lean Body Mass Estimate your muscle mass and see how it ranks against the US population.
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Arm Circumference Mid-upper arm circumference norms by age and sex from NHANES data.
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Strength-to-Weight Ratio How your lifts compare to bodyweight-based strength standards.

Body Girth & Adiposity

Waist, hip, WHR, and BMI. The measurements clinicians use most for cardiometabolic screening.

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Waist Circumference Abdominal fat measurement with WHO risk thresholds. Stronger predictor than BMI.
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Hip Circumference Hip measurement norms by age and sex from the NHANES survey.
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Waist-to-Hip Ratio Body fat distribution — apple vs pear shape — and associated health risks.
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BMI Percentile See where your BMI falls compared to US adults matched for age and sex.

Vital Signs & Cardiac

Resting heart rate, walking speed, and gait speed norms. Strong markers of cardiovascular fitness.

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Resting Heart Rate Lower is generally better. Compare your RHR to age and sex norms.
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Walking Speed A simple test strongly linked to longevity and functional independence.
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Gait Speed Norms Clinical reference values and fall risk assessment for adults 65+.

Body Shape Indices

Body Roundness Index and Waist-to-Height Ratio. Newer metrics that model fat distribution.

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Body Roundness Index JAMA 2024-validated body shape metric. Models your body as an ellipse.
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Waist-to-Height Ratio Simple rule: your waist should be less than half your height.

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.

All tools on this page 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.

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).