WVI methodology
How the daily Wellness Vitality Index is calculated.
Last updated: 2026-04-16
The score in one sentence
WVI is a 0-100 score that summarises how well your body recovered from yesterday and how prepared it is to perform today.
The 12 inputs
The score is a weighted geometric mean of 12 individually normalised metrics:
| Metric | Weight | Driven by |
|---|---|---|
| HRV | 16% | Heart rate variability (RMSSD) |
| Stress | 14% | SDK stress index (inverted) |
| Sleep | 13% | Total time, efficiency, deep sleep %, REM %, WASO |
| Emotional Wellbeing | 12% | 24h rolling emotion history + final multiplier |
| SpO2 | 8% | Blood oxygen saturation |
| Heart Rate | 7% | Delta from resting heart rate |
| Steps | 7% | Daily step count |
| Active Calories | 6% | Movement and training calories (excludes BMR) |
| Activity Load (ACWR) | 5% | Acute:Chronic Workload Ratio |
| Blood Pressure | 5% | Deviation from 120/80 mmHg baseline |
| Temperature | 4% | Deviation from personal baseline |
| PPI Coherence | 3% | Pulse-to-pulse interval regularity |
Why geometric mean
Unlike an arithmetic mean, the geometric mean prevents compensating a poor metric with excess in another. Bad sleep cannot be offset by a great workout.
Hard caps
Critical failures in any single metric set an absolute WVI ceiling. For example, fewer than 3,000 steps caps WVI at 45, and SpO2 below 92% caps it at 40, regardless of other metrics.
Progressive curve
Scoring is linear up to 60 (easy to reach), then uses an exponential ceiling. Reaching 80+ requires sustained excellence. True 100 is nearly impossible without peak performance in all 12 metrics plus a Flow emotional state.
18 emotions
Wellex detects 18 emotional states from biometric patterns. Each emotion applies a final multiplier between 0.78 (Exhausted) and 1.15 (Flow). Negative emotions carry stronger penalties than positive emotions carry boosts, reflecting the scientific finding that negative states impact health faster than positive states restore it.
Personalisation
The first 14 days are baselining. After that, every score is computed against your baseline, not a global one. Two members with identical raw biometrics can have different WVI scores because their bodies respond differently. Cold start uses Bayesian shrinkage to blend population priors with emerging personal data.
What WVI is not
It is not a fitness score, a productivity score, a happiness score or a longevity score. It is a recovery and readiness score for today.