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Official WHO, AHA, and ADA normal ranges for every metric tracked in VitalSync — blood pressure, heart rate, SpO₂, HRV, body temperature, blood sugar, HbA1c, sleep, and nutrition.
For informational and educational purposes only. VitalSync is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. All content presents health data against established clinical reference ranges. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment.
Clinical Reference Ranges
This article lists the official clinical reference ranges used by VitalSync to colour-code readings and generate reference bands. All ranges are sourced from the World Health Organization (WHO), American Heart Association (AHA), and American Diabetes Association (ADA). They represent population-level thresholds — individual targets may differ based on age, medical history, and your healthcare provider's guidance.
Important: These ranges are provided for informational and educational purposes only. VitalSync is not a medical device and does not diagnose, treat, cure, or prevent any medical condition. Always consult a qualified healthcare professional for personalised medical advice.
Blood Pressure
Source: AHA/ACC Hypertension Guideline 2017 (Whelton et al.) and WHO 2023| Category | Systolic (mmHg) | Diastolic (mmHg) |
| Normal | < 120 | < 80 |
| Elevated | 120–129 | < 80 |
| High — Stage 1 | 130–139 | 80–89 |
| High — Stage 2 | ≥ 140 | ≥ 90 |
| Hypertensive Crisis | > 180 | > 120 |
| Low (Hypotension) | < 90 | < 60 |
VitalSync uses the AHA 2017 threshold of 130/80 mmHg as the Stage 1 hypertension boundary, which replaced the older 140/90 mmHg threshold. The WHO 2023 report aligns with this classification for adults aged 18 and over.
Heart Rate (Resting)
Source: AHA; Palatini & Julius, 1997| Category | Beats per Minute (bpm) |
| Bradycardia (Low) | < 60 |
| Normal | 60–100 |
| Tachycardia (Elevated) | > 100 |
Well-trained athletes may have a resting heart rate of 40–60 bpm, which is considered normal for that population. VitalSync uses your personal 30-day rolling average as your individual baseline.
Blood Oxygen Saturation (SpO₂)
Source: WHO; British Thoracic Society| Category | SpO₂ (%) |
| Normal | 95–100 |
| Acceptable (some conditions) | 92–94 |
| Below normal reference range | < 92 |
Readings below 92% fall outside the normal reference range. Review any persistent readings in this range with a qualified healthcare professional.
Heart Rate Variability (HRV — RMSSD)
Source: Shaffer & Ginsberg, 2017 (Frontiers in Public Health)HRV is highly individual and age-dependent. The table below shows approximate population reference ranges by age group.
| Age Group | Low (ms) | Average (ms) | High (ms) |
| 20–29 | < 40 | 65–75 | > 100 |
| 30–39 | < 35 | 55–65 | > 90 |
| 40–49 | < 30 | 45–55 | > 80 |
| 50–59 | < 25 | 35–45 | > 70 |
| 60+ | < 20 | 25–35 | > 60 |
VitalSync uses your personal 7-day rolling average as your HRV baseline rather than population norms, because individual HRV varies significantly. Population ranges are shown here for general reference only.
Body Temperature
Source: Mackowiak et al., 1992 (JAMA); WHO| Category | Temperature (°C) | Temperature (°F) |
| Hypothermia | < 35.0 | < 95.0 |
| Low normal | 35.0–36.0 | 95.0–96.8 |
| Normal | 36.1–37.2 | 97.0–99.0 |
| Low-grade fever | 37.3–38.0 | 99.1–100.4 |
| Fever | 38.1–39.9 | 100.5–103.8 |
| High fever | ≥ 40.0 | ≥ 104.0 |
The traditional 37.0°C (98.6°F) figure is a population average. Normal body temperature varies by individual, time of day, and measurement site (oral, axillary, tympanic).
Blood Glucose
Source: ADA Standards of Medical Care in Diabetes 2024Fasting Blood Glucose
| Category | mg/dL | mmol/L |
| Normal | 70–99 | 3.9–5.5 |
| Pre-diabetic range | 100–125 | 5.6–6.9 |
| Diabetic reference range | ≥ 126 | ≥ 7.0 |
| Hypoglycaemia | < 70 | < 3.9 |
Post-Meal Blood Glucose (2 hours after eating)
| Category | mg/dL | mmol/L |
| Normal | < 140 | < 7.8 |
| Pre-diabetic range | 140–199 | 7.8–11.0 |
| Diabetic reference range | ≥ 200 | ≥ 11.1 |
HbA1c (Glycated Haemoglobin)
Source: ADA Standards of Medical Care in Diabetes 2024| Category | HbA1c (%) |
| Normal | < 5.7 |
| Pre-diabetic reference range | 5.7–6.4 |
| Diabetic reference range | ≥ 6.5 |
| ADA treatment target (diabetes) | < 7.0 |
VitalSync's projected A1C is a mathematical estimate derived from your logged glucose readings using the ADA eAG formula. It is not a laboratory HbA1c result. Always obtain an official HbA1c test from a clinical laboratory.
Sleep Duration
Source: American Academy of Sleep Medicine (AASM) / Watson et al., 2015| Age Group | Recommended Duration |
| Adults (18–60) | 7–9 hours per night |
| Older adults (61–64) | 7–9 hours per night |
| Seniors (65+) | 7–8 hours per night |
Sleep Efficiency
| Category | Efficiency (%) |
| Good | ≥ 85 |
| Acceptable | 75–84 |
| Poor | < 75 |
Body Mass Index (BMI)
Source: WHO BMI Classification| Category | BMI (kg/m²) |
| Underweight | < 18.5 |
| Normal weight | 18.5–24.9 |
| Overweight | 25.0–29.9 |
| Obese — Class I | 30.0–34.9 |
| Obese — Class II | 35.0–39.9 |
| Obese — Class III | ≥ 40.0 |
BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, or fat distribution. Consult a healthcare professional for a comprehensive body composition assessment.
Nutrition Reference Values
Source: WHO Nutrient Reference Values; AHA Dietary Guidelines| Nutrient | Daily Reference Value |
| Sodium | < 2,300 mg (AHA optimal: < 1,500 mg) |
| Potassium | 3,500–4,700 mg |
| Total Fat | 20–35% of total calories |
| Saturated Fat | < 10% of total calories (AHA: < 6%) |
| Total Carbohydrate | 45–65% of total calories |
| Dietary Fibre | 25–38 g (women: 25 g; men: 38 g) |
| Protein | 10–35% of total calories (0.8 g/kg body weight minimum) |
How VitalSync Uses These Ranges
VitalSync uses these published reference ranges to:
All observations are presented as data points against established reference ranges, not as diagnoses or treatment recommendations. Always review readings that fall outside these ranges with your healthcare provider.
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