The normal QRS axis lies between -30° and +90°. The heart's electrical activity points downward and to the patient's left, reflecting the dominant LV mass and standard conduction.
Common causes
•Healthy adults
•Mild variations with body habitus, age
Limb leads at axis 60°
Two-lead decision rule
Lead I
Positive
aVF
Positive
Lead II
Positive
→ Normal axis
Educational use only — not for clinical interpretation or patient care.