EKG Reading Calculator

Use lead II or V5 for most accurate QT interval measurements with clear T wave endpoints

Measure multiple beats and calculate average for irregular rhythms or atrial fibrillation

Standard EKG paper speed is 25 mm/s where each small square (1mm) = 0.04 seconds = 40ms

Identify clear T wave endpoint and avoid including U waves in QT measurement

Check electrolyte levels (potassium, calcium, magnesium) if QTc is prolonged

Review medication list for QT-prolonging drugs (antiarrhythmics, antibiotics, antipsychotics)

Normal QTc varies by gender: <450ms (men), <460ms (women). Values >500ms are concerning

Consider Fridericia or Framingham formulas for heart rates <60 or >100 bpm for better accuracy

Wide QRS (≥120ms) may indicate bundle branch block or ventricular rhythm - requires evaluation

Short PR interval (<120ms) may suggest pre-excitation (WPW syndrome) - needs cardiac workup