Health Formulas

Mifflin-St Jeor Equation (BMR)

The Mifflin-St Jeor equation calculates Basal Metabolic Rate (BMR) for men and women. More accurate than Harris-Benedict for most people.

Waist-to-Height Ratio (WHtR) Formula

The Waist-to-Height Ratio formula measures central obesity and cardiovascular health risk. Simpler and often more accurate than BMI.

Anion Gap Formula

Calculate the anion gap using AG = Na minus (Cl plus HCO3). Covers normal and elevated reference ranges and common causes of high anion gap metabolic acidosis.

Corrected Calcium Formula

Calculate albumin-corrected calcium: Ca_corrected = Ca_total + 0.8(4.0 - albumin). Essential for interpreting calcium levels in clinical medicine.

Du Bois Body Surface Area Formula

Calculate body surface area using the Du Bois formula: BSA = 0.007184 x W^0.425 x H^0.725. Used for drug dosing and burn assessment.

Karvonen Heart Rate Formula

Reference for the Karvonen heart rate reserve formula: THR = ((HRmax - HRrest) × intensity%) + HRrest. Covers HRmax estimation and zones.

Creatinine Clearance (Cockcroft-Gault)

Reference for the Cockcroft-Gault formula: CrCl = [(140 - age) × weight / (72 × creatinine)] × 0.85 for women. Returns CrCl for CKD staging and dosing.

Lean Body Mass Formula

Reference for lean body mass using the Boer, James, and Hume equations. Used in fitness planning, medication dosing, and body composition analysis.

Pregnancy Due Date Formula (Naegele's Rule)

Reference for Naegele's Rule: add 280 days to LMP for EDD. Covers EDD = LMP + 9 months + 7 days formula, trimester milestones, and ultrasound adjustments.

VO2 Max Formula

Reference for VO2 max using the Cooper test, Rockport walk, and Astrand bike test. Includes fitness ratings by age and sex and training zone calculations.

Blood Alcohol Content (BAC) Formula

Calculate estimated Blood Alcohol Content using the Widmark formula. Accounts for body weight, gender, alcohol consumed, and time elapsed.

BMI Formula (Body Mass Index)

Reference for the BMI formula: weight in kg divided by height in meters squared. Covers metric and imperial forms with WHO category thresholds and examples.

BMR Formula (Basal Metabolic Rate)

Calculate Basal Metabolic Rate using the Harris-Benedict equation. Separate formulas for men and women in both metric and imperial units.

Body Fat Percentage Formula (Navy Method)

Estimate body fat percentage using the U.S. Navy method with circumference measurements. Separate formulas for men and women in metric and imperial.

Caloric Needs Formula (TDEE)

Calculate Total Daily Energy Expenditure using TDEE = BMR × Activity Factor. Find how many calories you need per day based on your lifestyle.

Ideal Body Weight Formula (Devine)

Estimate ideal body weight using the Devine formula. Separate calculations for men and women using height in inches or centimetres.

Target Heart Rate Formula (Karvonen Method)

Calculate your target heart rate zone using the Karvonen formula. Optimise exercise intensity with THR = ((Max HR - Resting HR) × %Intensity) + Resting HR.

Waist-to-Hip Ratio Formula

Calculate waist-to-hip ratio (WHR) to assess health risk. A simple measurement used worldwide for both metric and imperial body measurements.