Normal QRS Range in Adults
The normal QRS duration in adults is ≤110 ms, with typical values ranging from 74-114 ms in males (average 95 ms), and QRS duration >110 ms is considered abnormal. 1
Age-Specific Normal Ranges
The normal QRS duration varies significantly by age group:
Adults (>16 years)
- Upper limit of normal: 110 ms 1
- Typical range in adult males: 74-114 ms (mean 95 ms) 1
- Values between 110-120 ms represent incomplete bundle branch block 1
- Values ≥120 ms indicate complete bundle branch block 1
Pediatric Populations
- Children <4 years: Normal <90 ms; ≥90 ms is prolonged 1
- Children 4-16 years: Normal <100 ms; ≥100 ms is prolonged 1
- Children 8-16 years: 80-90 ms represents incomplete LBBB range 1
Important Clinical Considerations
Sex differences matter clinically. Males typically have longer QRS durations than females at similar ages and body mass indices 2, 3. In a large cohort, median QRS was 92 ms in males versus 84 ms in females 3. This reflects smoother, less intricate depolarization propagation in females 2.
Body habitus influences QRS duration. Increasing BMI correlates positively with QRS duration independent of age, sex, and heart rate 3. The median QRS increases from 82 ms in underweight individuals (BMI <18.5) to 88 ms in obese individuals (BMI ≥30) 3.
Common Pitfalls to Avoid
Measurement technique matters: Global intervals (measured from spatial vector magnitude or superimposed complexes) are longer than single-lead measurements 1. QRS is wider in precordial leads than limb leads 1.
Heart rate effects: QRS duration decreases with increasing heart rate—for every 10 beat increase, duration drops by approximately 1.14 ms 4.
The 110 ms threshold is conservative: While some adult males may have QRS up to 114 ms, the guideline recommends using >110 ms as the abnormal cutoff to maintain diagnostic sensitivity 1.