Welcome! Our goal is to provide accurate and transparent health assessments. On this page, we detail the globally recognized formulas used in our calculator, showing how simple inputs can give meaningful insights into your body metrics.
By explaining each formula clearly, we aim to help you understand your results and make informed decisions about your health. From BMI to body fat percentage, every calculation is based on reliable scientific methods.
We also highlight important considerations and limitations, so you can interpret your results responsibly and in context. Whether you are tracking your fitness, monitoring your weight, or simply curious about health metrics, this guide will provide a clear and trustworthy reference.
The Body Mass Index (BMI) is a widely used screening tool to classify weight status based on height and weight.
$$\text{BMI} = \frac{\text{Mass (kg)}}{\text{Height (m)}^2}$$
Use SI units: kg and meters.The Body Mass Index (BMI) is a widely used metric to evaluate weight status and categorize individuals as underweight, normal weight, overweight, or obese. Although BMI does not measure body fat directly, it is a reliable, quick, and standard tool for adult health assessment.
BMI values are interpreted according to WHO classifications:
| Classification | BMI Range (kg/m²) |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 - 17 |
| Mild Thinness | 17 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese Class I | 30 - 35 |
| Obese Class II | 35 - 40 |
| Obese Class III | > 40 |
$$\text{BMR} = 10 \times M + 6.25 \times H - 5 \times A + S$$
Basal Metabolic Rate (BMR), calculated using the Mifflin-St Jeor equation, estimates the calories your body requires at rest to sustain essential functions such as breathing and circulation. Understanding your BMR is key for managing daily caloric intake and overall energy balance.
$$\text{TDEE} = \text{BMR} \times \text{Activity Multiplier}$$
Adjust BMR for daily activity level.Total Daily Energy Expenditure (TDEE) adjusts your BMR according to physical activity level to estimate the total calories burned per day. Knowing your TDEE helps plan nutrition, maintain energy balance, and manage body weight effectively.
$$\text{BFP} = 86.010 \times \log_{10}(\text{Waist} - \text{Neck}) - 70.041 \times \log_{10}(\text{Height}) + 36.76$$
The U.S. Navy Method for males estimates body fat percentage using waist and neck measurements. This non-invasive formula helps track body composition, monitor fat levels, and support overall health assessment.
$$\text{BFP} = 163.205 \times \log_{10}(\text{Waist} + \text{Hip} - \text{Neck}) - 97.684 \times \log_{10}(\text{Height}) - 78.387$$
The U.S. Navy Method for females estimates body fat percentage based on waist, hip, and neck measurements. It provides an accessible way to evaluate body composition, fat distribution, and general health.
$$P = \frac{\text{BMI}}{25}$$
BMI Prime (P) is a normalized index comparing your BMI to the upper limit of the healthy range. A BMI Prime of 1 indicates you are at the threshold of the normal BMI category, making it useful for quick body weight assessment.
$$\text{PI} = \frac{\text{Mass (kg)}}{\text{Height (m)}^3}$$
The Ponderal Index (PI) calculates body mass relative to the cube of height, offering a more precise assessment than BMI for very tall or short individuals. It evaluates body build, proportionality, and overall body composition.
These calculations provide helpful guidance but do not account for muscle mass, bone density, or fat distribution. Use results as general reference, not a medical diagnosis.
For detailed guidance, consult official resources like the CDC guidelines.
Disclaimer: All calculations are for informational purposes only and should not replace consultation with a qualified medical or nutrition professional.