ECG rhythm quiz: 12 strips
Name the rhythm, then see the one clue that gives it away. For student nurses and new nurses, in the UK (ECG) or the US (EKG).
For education and exam practice only. These are computer-drawn teaching strips of a single lead at standard paper speed, not real patient recordings. A rhythm strip never replaces looking at the patient. If someone is unwell or you are worried, get help and follow your local escalation policy. You remain accountable for your own practice. Last reviewed October 2026.
Six questions for any rhythm strip
Look at the patient first. Then ask the strip these six questions, in this order.
- Is anything happening? A flat line: check the patient, then the leads and the gain.
- Fast or slow? Normal is 60 to 100 a minute. (Some books and charts call it slow only under 50, so you will see both.) Count the big squares between two spikes and divide 300 by that number.
- Steady or wobbly? Mark three spikes on a scrap of paper and slide it along. If the marks still line up, it is regular.
- Skinny or fat? A normal QRS is narrow: under 3 small squares. A broad one started in the wrong place or took a detour.
- Any P waves? Look for a neat little bump before each spike. A wobbly line or a sawtooth is not a P wave.
- Are P and QRS a couple? One P before every QRS, with the same gap each time (3 to 5 small squares).
The paper
- One small square is 0.04 seconds. Five small squares make one big square: 0.2 seconds.
- Five big squares are one second.
- If the rhythm is uneven, count the spikes in 6 seconds (30 big squares) and multiply by 10.
Sources
The rhythm definitions and measurements on this page were checked in October 2026 against:
- Resuscitation Council UK, Adult advanced life support guidelines (2025)
- Life in the Fast Lane ECG Library: rate interpretation, PR interval, atrial fibrillation, atrial flutter, SVT, ventricular tachycardia and the AV block pages
Some sources count a heart rate under 50 as slow. This page uses under 60, as the Resuscitation Council UK does. Mobitz II is shown twice, once with narrow spikes and once with broad, because both are seen.
Want it explained first?
The full walk-through, How to read an ECG, and the short Guess the Rhythm quizzes are on YouTube. A printable ECG cheat sheet is on its way.