How your scores are calculated

Every number in ScoreVitals — the Daily Score, Readiness to Train, ACWR, your heart-rate zones — comes from a peer-reviewed formula, computed server-side from the health data your watch already collects. This page shows the exact weights, thresholds and research behind each one.

Composite metric

Daily Score

Your single 0–100 number each morning — a weighted picture of four research-backed health pillars. It's calculated automatically overnight in your local time zone, and again in real time whenever a new workout syncs.

Weighted composite

  • Cardio 40%
  • Sleep 30%
  • Recovery 20%
  • Body composition 10%

Each pillar is scored independently, then combined into one number. If a pillar has no data for the day, its weight is redistributed across the others rather than counted as zero.

Daily Score formula

Daily = 0.40·Cardio + 0.30·Sleep + 0.20·Recovery + 0.10·Body

Cardio
Training impulse (TRIMP) and time in productive heart-rate zones
Sleep
Duration, efficiency and consistency
Recovery
HRV and resting heart rate vs. your 7-day median
Body
Weight stability, composition quality and metabolic health

Hero feature

Readiness to Train

Your morning answer to “how hard should I train today” — a composite of recovery, sleep and training load, resolved into one of five levels with a heart-rate zone ceiling and a maximum session length.

Weighted composite

  • Recovery 50%
  • Sleep 30%
  • Training load (ACWR) 20%
The five readiness levels with score range, training zone, maximum session length and the app's guidance
Band Score Train up to Session What the app says
Ready to Push 85–100 Zone 5 Up to 90 min “You're recovered and primed. Today's the day for intervals, tempo, or your hardest session of the week. Don't waste it on something easy.”
Good to Train 70–84 Zone 4 Up to 75 min “Green light for your normal session. Steady cardio, a planned strength block, or a moderate workout — your body can handle it.”
Train Light 50–69 Zone 3 Up to 60 min “Hold back today. Keep heart rate moderate, focus on form, and skip the high-intensity work. A solid easy day now buys you a strong session tomorrow.”
Easy Day 33–49 Zone 2 Up to 45 min “Your body is asking for a soft day. Walk, cycle easy, mobility, or yoga — anything that moves blood without adding stress.”
Rest & Recover 0–32 Zone 1 Up to 30 min “Take the day off, or do recovery work only. Sleep, eat well, hydrate. Pushing through this score is how injuries happen.”

Safety override

When your acute:chronic workload ratio climbs above 1.5, a graduated penalty is applied to your readiness score — scaling from 0% at ACWR 1.5 up to 60% at ACWR 2.0 — and your training recommendation is held at Zone 3 or below until your load settles. This protects you from injury when training has ramped up too quickly.

Readiness formula

Readiness = 0.50·Recovery + 0.30·Sleep + 0.20·ACWR

Recovery
HRV and resting heart rate vs. your 7-day median, with a small trend bonus
Sleep
Duration, efficiency and stage quality from the last night
ACWR
Acute:chronic training-load ratio, highest around a ratio of 1.0–1.1
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The four pillars

Deep dive into each pillar

Open any pillar for its sub-weights, the tier thresholds that are actually shipping, and the research behind them.

Cardio & Session Score

Training load from every workout, scored per session and across the day

Cardio pillar — 40% of the Daily Score

  • TRIMP 60%

  • Time in heart-rate zones 3–5 40%

Light <50 TRIMP Moderate 50–99 Hard 100–149 Very hard 150–199 Extreme ≥200

Session Score — per workout

Computed the moment a workout syncs — within minutes on iPhone, about 30 minutes on Android.

  • TRIMP 60%

  • Efficiency 30%

  • Heart-rate recovery 10%

When no post-workout heart-rate sample is available, the recovery term is dropped and TRIMP + efficiency rescale to fill 100 — not silently padded with a neutral score.

Why heart rate, not just duration

TRIMP quantifies internal training load from heart-rate reserve — a 60-minute Zone 5 interval session scores dramatically higher than 60 minutes of walking, even though the duration is identical.

TRIMP formula (Banister, modified Edwards form)

TRIMP = t · HRR · ek·HRR

t
Workout duration in minutes
HRR
(Average HR − resting HR) ÷ (max HR − resting HR)
k
Gender coefficient — 1.92 male, 1.67 female

Sleep Score

How well you recovered overnight — duration, efficiency and consistency

Sleep pillar — 30% of the Daily Score

  • Duration 50%

  • Efficiency 35%

  • Consistency 15%

Duration targets by age (National Sleep Foundation)

Under 18 · 8–10h 18–25 · 7–9h 26–64 · 7–9h 65+ · 7–8h

Efficiency tiers (time asleep ÷ time in bed)

Low <75% Fair 75–85% Good 85–90% Excellent ≥90%

Readiness scores sleep differently

This 50/35/15 split is the Daily Score's Sleep pillar. Readiness to Train uses a separate sleep calculation — duration 50%, efficiency 30%, and deep & REM stage quality 20% — because how hard to train today depends on more than last night's total hours.

Recovery Score

Autonomic nervous system state via HRV and resting heart rate

Recovery pillar — 20% of the Daily Score

  • Heart-rate variability 60%

  • Resting heart rate 40%

Both are compared against your own personal 7-day median — yesterday back, so today's reading is never part of its own baseline — not a population average.

Two HRV metrics, one score

HRV is read as SDNN on iOS and RMSSD on Android — two different statistics from the same underlying signal. Both feed the same deviation-from-baseline formula, but expect a discontinuity if you switch platforms.

Body Composition Score

Weight stability, composition quality and metabolic health over a rolling 7-day window

Body Composition pillar — 10% of the Daily Score

  • Weight stability 40%

  • Composition quality 40%

  • Metabolic health 20%

Composition quality scores body-fat percentage against age- and sex-specific norms, cross-checked against lean body mass. Metabolic health validates your BMR (Mifflin–St Jeor), screens for “skinny fat”, and checks body-water percentage. BMI only steps in as a fallback when body-fat data isn't available.

Advanced metrics

ACWR — Training Pulse

Your acute (7-day) training load against your chronic (28-day) baseline, using exponentially weighted moving averages — the same ratio that drives the readiness override above.

100% ACWR
Acute (7d) Chronic (28d)
  • Under-Loaded <80%
  • Sweet Spot 80–130%
  • Caution 130–150%
  • High Risk >150%

New users aren't unfairly penalised

With fewer than 14 days of training history, ACWR is held at a neutral 100% (a ratio of 1.0) rather than computed from a zero-padded baseline — so a short history never counts against you.

ACWR formula

ACWR = EWMA7 ÷ EWMA28

EWMA7
Exponentially weighted moving average of daily TRIMP, 7-day window (acute load)
EWMA28
Same, 28-day window (chronic load)

Heart-rate zones (Karvonen method)

Five intensity zones from your heart-rate reserve — the gap between resting and maximum heart rate.

  • Recovery 50–60% HRR

  • Aerobic 60–70% HRR

  • Tempo 70–80% HRR

  • Threshold 80–90% HRR

  • Max 90–100% HRR

Karvonen formula

Target HR = HRrest + intensity · (HRmax − HRrest)

HRrest
Your resting heart rate
intensity
Zone boundary, 50–100% of heart-rate reserve
HRmax
Measured max HR, or the Tanaka estimate below
Tanaka formula (max HR)

HRmax = 208 − 0.7 · age

Used when
You haven't entered a measured max heart rate during setup

Heart-rate recovery

How many beats per minute your heart rate drops in the minutes after peak exertion — a marker of parasympathetic (vagal) reactivation.

  • Poor<12 bpm
  • Normal12–20 bpm
  • Excellent>20 bpm

Peak heart rate is the mean of your top five samples during the workout — a single spike can't inflate it. The 1-minute and 2-minute drops are then matched against post-workout samples with a 30-second tolerance.

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Methodology

The research behind every number

Every algorithm in ScoreVitals cites peer-reviewed exercise science. These are the seven papers and standards it's built on.

  1. Morton, Fitz-Clarke & Banister (1990) — the heart-rate-reserve TRIMP method that Banister's widely cited 1991 book chapter popularised (that chapter predates PubMed indexing and carries no PMID of its own; this is the paper its coefficients are drawn from). Used for training load and session scores. PubMed 2246166

  2. Gabbett (2016) — the acute:chronic workload ratio and its 0.8–1.3 sweet spot for injury-risk. Used for Training Pulse and the ACWR load alert. PubMed 26701923

  3. Karvonen, Kentala & Mustala (1957) — heart-rate zones from heart-rate reserve. Used for your five training zones. PubMed 13470504

  4. Tanaka, Monahan & Seals (2001) — maximum heart rate as 208 − 0.7 × age. Used when you haven't entered a measured max. PubMed 11153730

  5. Shaffer & Ginsberg (2017) — an overview of heart-rate variability metrics and normative ranges. Used for the recovery score. PubMed 29034226

  6. National Sleep Foundation — Hirshkowitz et al. (2015) — age-adjusted sleep duration targets. Used for the sleep pillar. PubMed 29073412

  7. Nes et al. (2011) and the ACSM running-speed equation — non-exercise and running-based VO2max estimation. Used for the Cardio Fitness band on your Profile. PubMed 21502897

Frequently asked questions

How is the ScoreVitals Daily Score calculated?

Your Daily Score (0-100) is a weighted composite of four health pillars: Cardio (40%), Sleep (30%), Recovery (20%), and Body Composition (10%). Each pillar is scored independently using peer-reviewed algorithms, then combined into a single daily number.

What is Readiness to Train?

Readiness to Train is a composite score combining Recovery (50%), Sleep (30%), and your ACWR training load ratio (20%). It ranges from 0-100 and tells you how hard to train today, with a target heart rate zone and duration recommendation. When your ACWR rises above 1.5, a graduated injury-risk penalty is applied and your recommendation is held at Zone 3 or below to protect you from an overtraining spike.

What is ACWR and how does it prevent injuries?

ACWR (Acute:Chronic Workload Ratio) compares your recent 7-day training load against your 28-day baseline using exponentially weighted moving averages. The sweet spot is 0.8-1.3. Above 1.5, research shows injury likelihood climbs 2-3x, and ScoreVitals applies a graduated penalty to your readiness score and holds your training recommendation to a recovery zone until your load comes back under control.

Ready to see your own scores?

Download ScoreVitals and your first daily readiness score is ready tomorrow morning.

Learn more about all ScoreVitals features or check device compatibility.

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