Health Calculator
Enter basic information
Required fields are used by the core formulas. If an optional field is blank, its related result will not be generated.
Health reference ranges
Chinese adult standards are used where available. Different ages, populations, and special conditions may require separate assessment.
| Measure | Reference range or threshold | Interpretation |
|---|---|---|
| BMI | <18.5 underweight; 18.5–23.9 normal; 24.0–27.9 overweight; ≥28.0 obesity | Screening thresholds for Chinese adults aged 18 and above. |
| Waist circumference | 85–89.9 cm for men and 80–84.9 cm for women indicate pre-central obesity; ≥90 cm for men and ≥85 cm for women indicate central obesity | Measurement site and technique affect the result. |
| Waist-to-height ratio | 0.5 is a commonly used simple adult threshold | “Keep your waist below half your height” is a screening message, not a diagnosis. |
| Waist-to-hip ratio | 0.90 for men and 0.85 for women are commonly used reference thresholds | Interpret together with waist circumference, BMI, and other risk factors. |
| Estimated body fat | 20%–25% for men and 25%–30% for women indicate higher body fat; ≥25% for men and ≥30% for women are high-body-fat alert values | Formula error can be substantial and cannot replace a body-composition assessment. |
| Resting heart rate | About 60–100 bpm is common for most adults | Athletes may be below 60; medication, emotion, and illness can also affect heart rate. |
| Blood pressure | Ideal below 120/80 mmHg; clinic readings ≥140/90 and home readings ≥135/85 meet hypertension screening thresholds | Below 90/60 suggests low blood pressure. One reading cannot diagnose a condition; repeat correctly. |
| Sleep duration | Generally 7–8 hours for adults; generally 6–7 hours for adults aged 65 and above | Duration is only one screening dimension; also consider sleep quality and how you feel after waking. |
| BMR, TDEE, BSA | No single universal “healthy range” | These are mainly estimates and trend-comparison measures, not stand-alone health thresholds. |
| BRI, conicity index, body water, blood volume, VO₂max | No universal alert threshold is applied on this page | These formulas are mainly for estimation or population comparison and cannot replace measurement or medical assessment. |
Main range sources: National Health Commission, Weight Management Guidelines (2024); National Health Commission weight-management guidance; Chinese primary-care hypertension guideline; National Health Commission sleep-health information; and the WHO waist circumference and waist–hip ratio report.
Formulas and sources
Expand each section to view formulas, input units, intended use, and original references.
1. BMI, BMI-based target weight, fat mass, and fat-free mass
Weight at a specified BMI = specified BMI × height (m)²
Weight gain needed when underweight = weight at BMI 18.5 − current weight
Weight loss needed when overweight or obese = current weight − weight at BMI 23.9
Fat mass = weight × body-fat percentage ÷ 100
Fat-free mass = weight − fat mass
BMI screens weight relative to height and does not directly distinguish fat from muscle. The gain or loss figure is only a mathematical conversion of the BMI reference range; no adjustment is shown when BMI is within range.
Sources: CDC BMI information; Chinese thresholds are from the National Health Commission guideline.
2. Primary CUN-BAE body-fat estimate and Deurenberg comparison
For men S=0; for women S=1.
Deurenberg for men = 1.2×BMI + 0.23×age − 16.2
Deurenberg for women = 1.2×BMI + 0.23×age − 5.4
The page uses CUN-BAE as the primary body-fat estimate and retains Deurenberg for comparison. The original CUN-BAE study covered ages 18–80 and a broad BMI range, but its sample was White. Either formula may differ from an individual measurement by several percentage points.
Sources: CUN-BAE development and validation study; Deurenberg et al., 1991.
3. WHtR, WHR, RFM, BAI, and ABSI
Waist-to-hip ratio = waist circumference ÷ hip circumference
RFM for men = 64 − 20×height÷waist circumference
RFM for women = 76 − 20×height÷waist circumference
BAI = hip circumference (cm) ÷ height (m)^1.5 − 18
ABSI = waist circumference (m) ÷ [BMI^(2/3) × height (m)^(1/2)]
These measures describe abdominal fat or body shape from different perspectives. Raw BAI and ABSI values vary substantially across populations and should not be used alone for diagnosis.
Sources: WHtR review; original RFM paper; BAI validation study; original ABSI paper.
4. Janmahasatian lean body mass and Mosteller body surface area
Female LBM = 9270×weight ÷ (8780 + 244×BMI)
BSA (m²) = √[height (cm)×weight (kg)÷3600]
The lean-body-mass formula is often used in research and medication-dosing contexts. Body surface area has no single health threshold for the general population.
Sources: lean-body-mass formula validation; Mosteller BSA formula.
5. Mifflin–St Jeor, Harris–Benedict, and Cunningham energy formulas
Mifflin for women = 10W + 6.25H − 5A − 161
Harris for men = 88.362 + 13.397W + 4.799H − 5.677A
Harris for women = 447.593 + 9.247W + 3.098H − 4.330A
Cunningham = 500 + 22×fat-free mass (kg)
W is weight in kg, H is height in cm, and A is age in years; results are in kcal/day. Strictly speaking, Mifflin estimates resting energy expenditure (REE). All three formulas are displayed for comparison.
Sources: original Mifflin paper; revised Harris–Benedict equation; original Cunningham paper.
6. TDEE and protein reference for exercising adults
Protein reference for exercising adults = weight (kg) × 1.4–2.0 g/day
PAL uses midpoints of the FAO adult activity ranges. The protein range applies to healthy exercising adults and is not a dietary prescription for everyone.
Sources: FAO human energy requirements; ISSN position stand on protein and exercise.
7. Maximum and target heart rates
Moderate-intensity target = 50%–70% of maximum heart rate
Vigorous-intensity target = 70%–85% of maximum heart rate
Karvonen target = resting heart rate + intensity×(maximum heart rate−resting heart rate)
Age-based formulas predict a group average; an individual's actual maximum heart rate may differ substantially. People with cardiovascular disease or medication that affects heart rate should follow medical advice.
Sources: original Tanaka paper; American Heart Association target heart rates.
8. Watson total body water and Nadler blood volume
Watson female TBW (L) = −2.097 + 0.1069×height (cm) + 0.2466×weight (kg)
Body-water percentage = TBW ÷ weight × 100%
Nadler male blood volume (L) = 0.3669×height (m)³ + 0.03219×weight (kg) + 0.6041
Nadler female blood volume (L) = 0.3561×height (m)³ + 0.03308×weight (kg) + 0.1833
Both are population equations based on anthropometric data. They do not represent current hydration or measured circulating blood volume and should not guide fluid replacement, blood donation, or medication dosing.
Sources: Watson body-water study; Nadler blood-volume study.
9. Body Roundness Index and conicity index
Conicity index = waist circumference (m) ÷ [0.109×√(weight in kg ÷ height in m)]
Both describe body shape or central fat distribution. Studies use different groupings or cut points, so this page does not apply a universal individual alert line.
Sources: original BRI study; conicity-index formula description.
10. Heart-rate reserve, estimated VO₂max, and exercise calories
Estimated VO₂max (ml/kg/min) = 15.3×estimated maximum heart rate÷resting heart rate
Exercise calories (kcal) = activity intensity matched by the system (MET)×3.5×weight (kg)÷200×minutes
The user selects an exercise type and duration; the calculator automatically matches a commonly used intensity. The Uth method originally uses measured maximum heart rate, while this page substitutes the Tanaka age equation, so errors can accumulate. Exercise calories also vary with individual efficiency and actual intensity.
Sources: Uth heart-rate-ratio method; 2024 Adult Compendium of Physical Activities.
11. Blood-pressure and sleep-duration assessment
Clinic hypertension screening threshold: systolic ≥ 140 or diastolic ≥ 90 mmHg
Home hypertension screening threshold: systolic ≥ 135 or diastolic ≥ 85 mmHg
Low reference: systolic < 90 or diastolic < 60 mmHg
Sleep-duration reference: 7–8 hours for adults; 6–7 hours for adults aged 65 and above
Blood pressure is assessed using the threshold for the selected measurement setting, with separate up or down arrows for systolic and diastolic readings. One reading cannot diagnose hypertension or hypotension. Sleep duration alone also does not represent sleep quality.
Sources: Chinese primary-care hypertension guideline; National Health Commission sleep-health information.