Biomedical Engineering / Subcategory
Physiological Systems
Physiological systems calculators and formulas for cardiovascular and fluid transport in the body. Includes cardiac output, blood flow rate, and Poiseuille's law calculations.
40Formulas
All levels Difficulty
Updated Oct 2026
← All Biomedical Engineering (44) Physiological Systems (40)
Fundamental
Glasgow Coma Scale Total Score
GCS = Eye + Verbal + Motor
Fundamental
TENS Unit Duty Cycle
Duty cycle (%) = (Pulse width / Pulse period) * 100
Fundamental
Medical Device Battery Life Estimate
Life (hr) = Battery capacity (mAh) / Device draw (mA)
Fundamental
Ultrasound Axial Resolution
Axial resolution = SPL / 2
Fundamental
Pulse Oximeter Perfusion Index
PI = (AC / DC) * 100
Fundamental
Insulin Pump Basal Rate
Basal rate (units/hr) = TDD * 0.5 / 24
Fundamental
Defibrillator Pediatric Energy Dose
Energy (J) = 2 to 4 J/kg * mass (kg)
Fundamental
Hearing Aid Gain
Gain (dB) = Output SPL - Input SPL
Fundamental
Hearing Threshold Level Conversion
dB HL = SPL(dB) - Reference SPL at that frequency
Fundamental
Body Temperature Conversion (°F to °C)
°C = (°F - 32) * 5/9
Fundamental
Blood Glucose Unit Conversion
mmol/L = mg/dL / 18.0
Fundamental
Nebulizer Medication Dose
Dose (mg) = Concentration (mg/mL) * Volume (mL)
Fundamental
Ventilator Tidal Volume (Lung-Protective)
VT = IBW * 6 (to 8) mL/kg
Fundamental
Oxygen Cylinder Duration
Duration (min) = (Cylinder_PSI - Safety_PSI) * Conversion_factor / Flow_rate
Fundamental
IV Drip Rate (Gravity Infusion)
Drip rate (gtt/min) = (Volume_mL * Drop_factor) / Time_min
Fundamental
Estimated VO2 Max (Non-Exercise, Simplified)
VO2max ≈ 15 * (HRmax / HRrest)
Fundamental
Body Surface Area (Mosteller Formula)
BSA = sqrt((height_cm * mass_kg) / 3600)
Fundamental
Cardiac Output
CO = SV * HR
Fundamental
Corrected QT Interval (Bazett's Formula)
QTc = QT / sqrt(RR)
Fundamental
Standard Drink Alcohol Units
Units = (volume_mL * %ABV) / 1000
Fundamental
Insulin-to-Carbohydrate Ratio Dosing
Insulin dose (units) = carb_grams / insulin_to_carb_ratio
Fundamental
Ovulation / Fertile Window Estimate
Ovulation day ≈ Cycle length - 14
Fundamental
Blood Alcohol Content (Widmark Formula)
BAC = (alcohol_grams / (mass_kg * r)) * 100 - (0.015 * hours)
Fundamental
Pulse Pressure
PP = SBP - DBP
Fundamental
Mean Arterial Pressure
MAP = DBP + (1/3)*(SBP - DBP)
Fundamental
Creatinine Clearance (Cockcroft-Gault)
CrCl = ((140-age)*mass) / (72*Scr) (×0.85 for women)
Fundamental
Glycemic Load
GL = (GI * carb_grams) / 100
Fundamental
Daily Protein Requirement
Protein (g) = mass(kg) * factor (factor ≈ 0.8 sedentary, 1.2-2.0 active/athletic)
Fundamental
Daily Water Intake Recommendation
Water (mL) = mass(kg) * 30
Fundamental
Pregnancy Due Date (Naegele's Rule)
Due date = Last menstrual period + 280 days
Fundamental
Body Fat Percentage (U.S. Navy Method, Men)
BF% = 495 / (1.0324 - 0.19077*log10(waist-neck) + 0.15456*log10(height)) - 450
Fundamental
Waist-to-Hip Ratio
WHR = waist_circumference / hip_circumference
Fundamental
Ideal Body Weight (Devine Formula)
IBW(men) = 50 + 2.3*(height_in - 60); IBW(women) = 45.5 + 2.3*(height_in - 60)
Fundamental
Calories Burned During Exercise (MET Formula)
Calories = MET * mass(kg) * duration(hours)
Fundamental
Target Heart Rate (Karvonen Formula)
THR = ((HRmax - HRrest) * intensity) + HRrest
Fundamental
Estimated Maximum Heart Rate
HRmax = 220 - age
Fundamental
Total Daily Energy Expenditure (TDEE)
TDEE = BMR * activity_factor
Fundamental
Basal Metabolic Rate (Mifflin-St Jeor)
BMR = 10*mass + 6.25*height - 5*age + s (s = +5 for men, -161 for women)
Fundamental
Body Mass Index (BMI)
BMI = mass / height²
Fundamental
Poiseuille's Law
Q = πΔPr⁴ / (8ηL)