Methodology
This page explains how each tool calculates its results. We believe in transparency — you should know exactly what your score means and how it is derived. These tools are for personal wellness tracking only and are not diagnostic instruments.
Sleep Debt Calculator
What It Measures
Sleep Debt estimates the cumulative deficit between your actual sleep and a recommended baseline over the past 7 days.
Calculation
- Recommended baseline: 7–9 hours per night (aligned with National Sleep Foundation and CDC guidelines)
- For each of the last 7 nights, the calculator compares your reported sleep to the 7-hour minimum
- Hours below 7 are accumulated as debt
- Hours at or above 7 do not reduce existing debt (sleep debt is not recovered by oversleeping)
- Total debt is displayed as hours lost
Formula: Sleep Debt = Σ max(0, 7 − reported hours) over 7 days
Limitations
- Self-reported sleep data may not match objective measurements
- Individual sleep needs vary — 7 hours is a general guideline, not a universal target
- Does not account for sleep quality, interruptions, or sleep efficiency
Energy Score
What It Measures
Energy Score is a composite metric that tracks your self-reported energy levels alongside influencing factors — sleep, stress, and activity — over a single day.
Calculation
- Base score starts at 100
- Sleep quality: −0 to −20 points based on how well you slept the previous night
- Stress level: −0 to −20 points based on your reported stress
- Activity level: −0 to −20 points (very high or very low activity may reduce score)
- Final score = 100 − total deductions
- Scores above 80 are considered good; scores below 50 may warrant attention
Limitations
- Entirely subjective — based on your perception of energy, sleep, and stress
- Not a medical assessment
- Designed for day-to-day personal trend tracking, not clinical use
Recovery Score
What It Measures
Recovery Score evaluates how well your body is recovering based on four dimensions: sleep, stress, exercise, and caffeine intake.
Calculation
- Base score starts at 100
- Sleep deduction: −0 to −25 based on hours of sleep (less than 7 hours = higher deduction)
- Stress deduction: −0 to −25 based on reported stress level
- Exercise deduction: −0 to −15 (too little or too much exercise increases deduction)
- Caffeine deduction: −0 to −10 based on caffeine intake after 2 PM
- Final score = 100 − sum of all deductions
Limitations
- Recovery needs vary significantly by individual
- Does not account for nutrition quality, hydration, or medical conditions
- Self-reported data may not reflect physiological recovery state
BMI Calculator
What It Measures
Body Mass Index (BMI) is a height-to-weight ratio commonly used as a screening tool for body weight categories.
Calculation
- Metric: BMI = weight (kg) / height (m)²
- Imperial: BMI = (weight (lbs) / height (in)²) × 703
- Categories follow standard WHO classifications: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), Obese (≥30)
Limitations
- BMI does not distinguish between fat and muscle mass
- May overestimate body fat in athletes and underestimate it in older adults
- Not a diagnostic tool — consult a healthcare provider for a full assessment
Sources and References
Our calculation models and content are informed by:
- National Sleep Foundation — sleep duration guidelines
- Centers for Disease Control and Prevention (CDC) — sleep and health
- World Health Organization (WHO) — BMI classifications
- Traditional East Asian food therapy texts including the Huangdi Neijing
- Published research on sleep, energy, and recovery physiology
Updates
We review and update our methodology periodically as new research emerges. Last updated: July 2026.