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EKG Quiz

A free ECG practice test with answers. Twenty questions that mix real rhythm strips with the EKG basics, and a source behind every answer.

  • Real ECG strips
  • Calipers and magnifier
  • Full 12-lead view
  • No sign-up

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What this ECG practice test covers

This EKG quiz mixes reading real tracings with the fundamentals every ECG reader needs. Each run is 20 questions, 8 on rhythm strips and 12 on the EKG basics, in these areas:

  • Rhythm strips (949 real 10-second recordings): naming the rhythm and measuring the PR, the QRS and the rate.
  • The paper (7 questions in the bank): small and large boxes, paper speed and calibration.
  • Waves, segments and intervals (13 questions in the bank): the P wave, QRS complex, T wave, PR and QT intervals, and the J point.
  • Normal values (4 questions in the bank): normal PR, QRS and QT measurements.
  • Heart rate (3 questions in the bank): working out the heart rate from the paper.
  • Leads and electrodes (8 questions in the bank): the 12 leads, what each one looks at, and where the electrodes go.
  • Conduction and rhythm (5 questions in the bank): the conduction system and the signs of sinus rhythm.

The rhythms on these EKG strips

Every strip is a real recording, shown at 25 mm/s and 10 mm/mV, with calipers, a magnifier and the whole 12-lead one click away. These are the ECG rhythms you may meet, each linked to its definition in the EKG Dictionary.

More ways to practice for an EKG exam

EKG Practice Strips has more real rhythm strips to read step by step, with answers and no sign-up. The EKG Cheat Sheet puts sixteen rhythms on one printable page. Rhythm Foundations teaches eleven common ECG rhythms, and the EKG Dictionary defines each term with its sources.

Questions about this EKG and ECG quiz

Is an EKG the same as an ECG?

Yes. They are two names for the same test, the electrocardiogram. EKG comes from the German spelling and is common in the United States; ECG is used in most other countries. EKGLab uses both.

Is this EKG quiz free?

Yes. The quiz, its answers and its sources are free, and you do not need an account. Nothing you answer is saved or sent.

How many questions are on this ECG practice test?

Each run is 20 questions: 8 on real ECG strips and 12 on the EKG basics, drawn at random, so you can take it more than once. Every EKG basics question in the bank is listed on this page with its answer.

Can I measure on the EKG strips?

Yes. Every strip has calipers for measuring intervals and a magnifier, and a button that opens the whole 12-lead ECG the strip came from.

What score do I need to pass?

EKGLab's quizzes pass at 80%.

Where do the answers come from?

Every EKG basics answer shows its sources: hover over or tap a small number in an explanation to read the source's own words. Every strip is a real recording, checked against the measurements the 12-lead machine made on it, with the EKG Dictionary's definition and sources after you answer.

Will this help me study for an EKG exam?

EKGLab is practice: reading real rhythm strips and 12-leads, with feedback on every answer. It is not a certification course and does not award a certificate. This quiz covers the fundamentals. It is not a certification exam such as the NHA CET, and EKGLab is not affiliated with any certifying body.

EKG quiz questions and answers

Every EKG basics question in the bank (40), with its answer, its explanation and its sources.

The paper

What is the usual standard paper speed for recording an EKG?

  • 10 millimeters per second
  • 25 millimeters per second
  • 50 millimeters per second
  • 100 millimeters per second
Show the answer

Answer: 25 millimeters per second

The usual standard paper speed is 25 millimeters per second. Some countries use 50 millimeters per second as standard, and the rule for working out the heart rate changes with it.

Sources: Meek 2002a, BMJ; Sattar 2023, StatPearls

One small box is ____ seconds wide, and one large box is ____ seconds wide.

Show the answer

Answer: One small box is 0.04 seconds wide, and one large box is 0.20 seconds wide.

At 25 millimeters per second a small box (1 millimeter) lasts 0.04 seconds. A large box is five small boxes wide, so it lasts 0.20 seconds.

Sources: Meek 2002a, BMJ

At the standard paper speed, how many large boxes pass in one second?

Show the answer

Answer: 5 large boxes

Each large box lasts 0.20 seconds, so five large boxes make one full second.

Sources: Meek 2002a, BMJ

At the standard calibration, how tall is a signal of 1 millivolt?

  • 1 millimeter (one small box)
  • 5 millimeters (one large box)
  • 10 millimeters (two large boxes)
  • 20 millimeters (four large boxes)
Show the answer

Answer: 10 millimeters (two large boxes)

The standard calibration is 10 millimeters per millivolt, so a 1 millivolt signal stands 10 millimeters tall, which is two large boxes. Analog machines need the calibration verified, and computerized machines verify it automatically.

Sources: Meek 2002a, BMJ; Samesima 2022, Arq Bras Cardiol

At the standard calibration, a wave that is 5 millimeters tall (one large box) measures 0.5 millivolt.

  • True
  • False
Show the answer

Answer: True

At 10 millimeters per millivolt, each small box is 0.1 millivolt tall, so the five small boxes of one large box add up to 0.5 millivolt.

Sources: Meek 2002a, BMJ

What do the two directions on EKG paper measure?

  • Left to right is time, and up and down is voltage
  • Left to right is voltage, and up and down is time
  • Left to right is heart rate, and up and down is time
  • Left to right is time, and up and down is blood pressure
Show the answer

Answer: Left to right is time, and up and down is voltage

Time runs from left to right, so the width of a wave is how long it lasts, in seconds. Height is voltage (also called amplitude), measured in millivolts.

Sources: Sattar 2023, StatPearls; Meek 2002a, BMJ

How many seconds of recording does a standard 12-lead EKG printout show?

  • 2.5 seconds
  • 6 seconds
  • 10 seconds
  • 60 seconds
Show the answer

Answer: 10 seconds

A standard 12-lead printout covers 10 seconds. In the usual layout each of its four columns shows 2.5 seconds of three leads, and a rhythm strip along the bottom, when the page has one, runs the full 10 seconds.

Sources: Sattar 2023, StatPearls; Kligfield 2007, Circulation

Waves, segments and intervals

Match each wave with the event it represents.

Match each with its answer:

  • P wave
  • QRS complex
  • T wave
Show the answer

Answer: P wave: Atrial depolarization; QRS complex: Ventricular depolarization; T wave: Ventricular repolarization

The P wave is atrial depolarization, the QRS complex is ventricular depolarization and the T wave is ventricular repolarization.

Sources: Meek 2002b, BMJ

Match each wave of the QRS complex with how it is named.

Match each with its answer:

  • Q wave
  • R wave
  • S wave
Show the answer

Answer: Q wave: The first downward deflection, before any R wave; R wave: An upward deflection; S wave: A downward deflection that follows an R wave

The waves of a QRS complex are named by their direction and their order: a Q wave is a downward deflection that comes before any R wave, an R wave is an upward deflection, and an S wave is a downward deflection that follows an R wave. Not every QRS complex has all three: the S wave, for example, is often absent in leads V5 and V6.

Sources: Meek 2002b, BMJ

Which term means the electrical activation of heart muscle cells, the event that normally triggers contraction?

  • Repolarization
  • Automaticity
  • Refractory period
  • Depolarization
Show the answer

Answer: Depolarization

Depolarization is the electrical activation of the heart muscle, and it is what sets off contraction. Repolarization is its electrical recovery, which leaves the cells ready for the next beat.

Sources: Meek 2002a, BMJ; Wei 2023, StatPearls; Open RN 2023, Nursing Advanced Skills; Rogoff 2022, StatPearls

What is the small, low wave that sometimes follows the T wave called?

  • J wave
  • U wave
  • Delta wave
  • Q wave
Show the answer

Answer: U wave

The U wave is a small, low deflection that may follow the T wave. Many EKGs show no clear U wave, and when it is present it is seen best in leads V2 and V3 and at slower heart rates.

Sources: Rautaharju 2009, Circulation; Meek 2002b, BMJ

What is the name of the point where the QRS complex ends and the ST segment begins?

Show the answer

Answer: J point

The J point is the junction where the QRS complex ends and the ST segment begins. ST elevation and ST depression are usually measured there, against the baseline.

Sources: Meek 2002b, BMJ; Rautaharju 2009, Circulation

Between which two points is the PR interval measured?

  • From the end of the P wave to the start of the QRS complex
  • From the start of the P wave to the end of the QRS complex
  • From the end of the QRS complex to the start of the T wave
  • From the start of the P wave to the start of the QRS complex
Show the answer

Answer: From the start of the P wave to the start of the QRS complex

The PR interval runs from the start of the P wave to the start of the QRS complex, whether the QRS complex begins with a Q wave or an R wave. The flat stretch from the end of the P wave to the QRS complex is the PR segment.

Sources: Meek 2002b, BMJ

The PR ____ is the stretch of line between the P wave and the QRS complex. The PR ____ runs from the start of the P wave, so it includes the P wave.

Show the answer

Answer: The PR segment is the stretch of line between the P wave and the QRS complex. The PR interval runs from the start of the P wave, so it includes the P wave.

The PR segment is the line after the P wave, up to the QRS complex. The PR interval starts at the beginning of the P wave, so it contains that wave. The ST segment and the QT interval differ in the same way: the ST segment is the line between the QRS complex and the T wave, and the QT interval includes both of those waves.

Sources: Meek 2002b, BMJ

Where does the ST segment begin and end?

  • From the end of the QRS complex to the start of the T wave
  • From the start of the QRS complex to the end of the T wave
  • From the end of the T wave to the start of the next P wave
  • From the end of the P wave to the start of the QRS complex
Show the answer

Answer: From the end of the QRS complex to the start of the T wave

The ST segment runs from the end of the QRS complex to the start of the T wave. It is normally about level with the baseline, though some elevation at its start is normal in most chest leads.

Sources: Meek 2002b, BMJ; Wagner 2009, Circulation; Rautaharju 2009, Circulation

Between which two points is the QT interval measured?

  • From the start of the QRS complex to the start of the T wave
  • From the end of the QRS complex to the end of the T wave
  • From the start of the QRS complex to the end of the T wave
  • From the start of the P wave to the end of the T wave
Show the answer

Answer: From the start of the QRS complex to the end of the T wave

The QT interval runs from the start of the QRS complex to the end of the T wave. It covers the whole of ventricular depolarization and repolarization.

Sources: Meek 2002b, BMJ

Why is the QT interval usually reported as a corrected QT interval (QTc)?

  • Because the QT interval changes with the height of the patient
  • Because the T wave is too small to measure directly
  • Because every machine prints at a different paper speed
  • Because the QT interval changes with the heart rate
Show the answer

Answer: Because the QT interval changes with the heart rate

The QT interval lengthens as the heart rate slows and shortens as it speeds up. A formula such as Bazett's corrects it for the rate, and the result is written QTc.

Sources: Meek 2002b, BMJ; Sattar 2023, StatPearls

What is the R-R interval?

  • The height of an R wave above the baseline
  • The time between two consecutive R waves
  • The time from an R wave to the end of the T wave
  • The width of a single R wave
Show the answer

Answer: The time between two consecutive R waves

The R-R interval is the time between two consecutive R waves. It is the basis for working out the ventricular rate.

Sources: Meek 2002b, BMJ; Meek 2002a, BMJ

What is the isoelectric line?

  • The flat baseline of the tracing, against which the waves are measured
  • The peak of the tallest R wave
  • The line that marks each second on the paper
  • The calibration mark at the start of the tracing
Show the answer

Answer: The flat baseline of the tracing, against which the waves are measured

The isoelectric line is the flat baseline of the tracing. Waves are read as upward or downward from it, and ST segment shifts and T wave heights are measured against the TP or PR segment, which normally lie on it.

Sources: Open RN 2023, Nursing Advanced Skills; Rautaharju 2009, Circulation; Meek 2002a, BMJ; Meek 2002b, BMJ

A normal EKG shows a separate wave for atrial repolarization.

  • True
  • False
Show the answer

Answer: False

The atrial repolarization wave, called the Ta wave, is usually hidden by the much larger QRS complex and T wave. So a normal EKG does not show it as a separate wave. It can be recorded in third-degree AV block, when the Ta wave and the QRS complexes are uncoupled.

Sources: Holmqvist 2009, Ann Noninvasive Electrocardiol; Wei 2023, StatPearls

Normal values

What is the normal range of the PR interval in an adult?

  • 0.04 to 0.10 seconds
  • 0.12 to 0.20 seconds
  • 0.20 to 0.30 seconds
  • 0.36 to 0.44 seconds
Show the answer

Answer: 0.12 to 0.20 seconds

The normal adult PR interval is 0.12 to 0.20 seconds (120 to 200 milliseconds), which is three to five small boxes at the standard paper speed, and it varies with age and heart rate.

Sources: Meek 2002b, BMJ; Samesima 2022, Arq Bras Cardiol

A PR interval spans 4 small boxes at the standard paper speed. How long is it, in seconds?

Show the answer

Answer: 0.16 seconds

Each small box is 0.04 seconds, so four small boxes are 0.16 seconds (160 milliseconds).

Sources: Meek 2002a, BMJ

A QRS complex is described as wide when it lasts at least how long?

  • 0.04 seconds (one small box)
  • 0.08 seconds (two small boxes)
  • 0.12 seconds (three small boxes)
  • 0.20 seconds (five small boxes)
Show the answer

Answer: 0.12 seconds (three small boxes)

A QRS complex that lasts 0.12 seconds (120 milliseconds, three small boxes) or more is called wide. A QRS complex shorter than that is usually called narrow.

Sources: Meek 2002b, BMJ; Samesima 2022, Arq Bras Cardiol; Sattar 2023, StatPearls

A heart rate below ____ beats per minute is called bradycardia, and a heart rate above ____ beats per minute is called tachycardia.

Show the answer

Answer: A heart rate below 60 beats per minute is called bradycardia, and a heart rate above 100 beats per minute is called tachycardia.

By the traditional definitions, bradycardia is a heart rate below 60 beats per minute and tachycardia is a heart rate above 100 beats per minute. For its own purposes the 2018 bradycardia guideline uses a lower figure, a sinus rate below 50 beats per minute, and the 2022 Brazilian guideline defines sinus bradycardia the same way.

Sources: Meek 2002a, BMJ; Kusumoto 2019, Circulation; Samesima 2022, Arq Bras Cardiol

Heart rate

In a regular rhythm at the standard paper speed, consecutive R waves are 4 large boxes apart. What is the heart rate?

Show the answer

Answer: 75 beats per minute

Divide 300 by the number of large boxes between two consecutive R waves: 300 divided by 4 is 75 beats per minute.

Sources: Meek 2002a, BMJ

To find the atrial rate rather than the ventricular rate, which waves do you count?

  • QRS complexes
  • T waves
  • U waves
  • P waves
Show the answer

Answer: P waves

The atrial rate is the number of P waves per minute, and the ventricular rate is the number of QRS complexes per minute. In a normal rhythm a P wave comes before each QRS complex, so the two are the same, but a dysrhythmia can make them differ.

Sources: Open RN 2023, Nursing Advanced Skills; Rogoff 2022, StatPearls

A 6 second strip of an irregular rhythm contains 7 QRS complexes. What is the estimated heart rate?

Show the answer

Answer: 70 beats per minute

For an irregular rhythm such as atrial fibrillation, count the QRS complexes in a 6 second strip (30 large boxes) and multiply by 10: 7 times 10 is 70 beats per minute.

Sources: Open RN 2023, Nursing Advanced Skills; Samesima 2022, Arq Bras Cardiol

Leads and electrodes

Sort each lead into its group.

Sort into Limb leads and Chest (precordial) leads:

  • aVL
  • Lead I
  • Lead III
  • V1
  • V3
  • V6
Show the answer

Answer: Lead I: Limb leads; V6: Chest (precordial) leads; Lead III: Limb leads; V3: Chest (precordial) leads; aVL: Limb leads; V1: Chest (precordial) leads

The six limb leads are I, II, III, aVR, aVL and aVF, and they view the heart in the frontal (vertical) plane. The six chest (precordial) leads are V1 through V6, and they view it in the horizontal plane.

Sources: Meek 2002a, BMJ; Kligfield 2007, Circulation

When a wave of depolarization travels toward the positive electrode of a lead, what does that lead record?

  • A downward (negative) deflection
  • A flat line
  • An upward (positive) deflection
  • A wider QRS complex
Show the answer

Answer: An upward (positive) deflection

Depolarization that travels toward the positive electrode of a lead is recorded as an upward deflection, and depolarization that travels away from it as a downward deflection.

Sources: Kligfield 2007, Circulation; Sattar 2023, StatPearls

Which group of leads views the inferior (lower) surface of the heart?

  • Leads II, III and aVF
  • Leads I, aVL, V5 and V6
  • Leads V1 through V4
  • Leads aVR and V1
Show the answer

Answer: Leads II, III and aVF

Leads II, III and aVF view the inferior surface of the heart. Leads I, aVL, V5 and V6 view the lateral surface, and leads V1 through V4 view the anterior surface. Some references call V1 and V2 the septal leads, and V3 and V4 the anterior leads.

Sources: Meek 2002a, BMJ; Open RN 2023, Nursing Advanced Skills

Where is the V1 electrode placed?

  • In the fourth intercostal space at the left border of the sternum
  • In the fourth intercostal space at the right border of the sternum
  • In the fifth intercostal space in the midclavicular line
  • In the second intercostal space at the right border of the sternum
Show the answer

Answer: In the fourth intercostal space at the right border of the sternum

V1 is placed in the fourth intercostal space at the right border of the sternum, and V2 in the same space at the left border. V4 is placed in the fifth intercostal space in the midclavicular line.

Sources: Kligfield 2007, Circulation

Which lead is most commonly used for a rhythm strip?

  • I
  • II
  • III
  • aVL
  • aVR
  • aVF
Show the answer

Answer: II

Lead II is the usual choice for a rhythm strip, because it usually gives a good view of the P wave.

Sources: Meek 2002a, BMJ

Placing EKG electrodes in the wrong position can change the shape of the waves on the tracing.

  • True
  • False
Show the answer

Answer: True

Misplaced chest electrodes can change the waves on a tracing a great deal. Placing V1 and V2 too high can shrink the first R wave in those leads. A related error, swapping the left and right arm wires, inverts lead I. Limb lead switches can also give false-positive and false-negative signs of ischemia.

Sources: Kligfield 2007, Circulation

Every printed EKG is diagnostic quality and suitable for measuring the ST segment.

  • True
  • False
Show the answer

Answer: False

Not every printed EKG is diagnostic quality: filtering to a band of 1 to 30 Hz gives a stable tracing, but that bandwidth is unacceptable for diagnostic recording. With traditional analog filters, a 0.5 Hz low-frequency cutoff, once widely used in rhythm monitors, can distort repolarization and produce false ST deviation. To reduce that distortion, the AHA standard sets the low-frequency cutoff at 0.05 Hz, or at 0.67 Hz or below for digital filters designed to avoid it.

Sources: Kligfield 2007, Circulation

Conduction and rhythm

Put the parts of the conduction system in the order a normal impulse travels through them.

  • Atrioventricular (AV) node
  • Bundle of His
  • Purkinje fibers
  • Right and left bundle branches
  • Sinoatrial (SA) node
Show the answer

Answer: 1. Sinoatrial (SA) node; 2. Atrioventricular (AV) node; 3. Bundle of His; 4. Right and left bundle branches; 5. Purkinje fibers

A normal impulse begins in the sinoatrial node and spreads across the atria to the atrioventricular node, where it pauses briefly. It then travels down the bundle of His, through the right and left bundle branches and into the Purkinje fibers, which activate the ventricles.

Sources: Meek 2002a, BMJ; Rogoff 2022, StatPearls

Match each pacemaker site with its usual built-in rate.

Match each with its answer:

  • Sinoatrial (SA) node
  • Atrioventricular (AV) junction
  • Ventricles
Show the answer

Answer: Sinoatrial (SA) node: 60 to 100 beats per minute; Atrioventricular (AV) junction: 40 to 60 beats per minute; Ventricles: 20 to 40 beats per minute

The sinoatrial node fires fastest, at about 60 to 100 beats per minute, so it normally sets the pace. If its impulses fail to form or to arrive, a slower site lower down can take over: about 40 to 60 beats per minute from the atrioventricular junction and about 20 to 40 from the ventricles. Sources differ a little on the lower ranges: one gives 40 to 50 for the junction and 30 to 40 for the ventricles.

Sources: Wei 2023, StatPearls; Sattar 2023, StatPearls; Open RN 2023, Nursing Advanced Skills; Rogoff 2022, StatPearls; Ashkanani 2026, Ann Noninvasive Electrocardiol

Which of these are features of normal sinus rhythm?

  • A P wave before every QRS complex
  • A rate of 60 to 100 beats per minute
  • Upright P waves in lead II
  • A PR interval that gets longer with each beat
  • No visible P waves
Show the answer

Answer: A P wave before every QRS complex, A rate of 60 to 100 beats per minute, Upright P waves in lead II

Normal sinus rhythm begins in the sinoatrial node. It has upright P waves in leads I and II, a P wave before every QRS complex and a PR interval of 0.12 to 0.20 seconds. By the traditional definition its rate is 60 to 100 beats per minute, and it is regular apart from the normal change with breathing.

Sources: Meek 2002a, BMJ; Rogoff 2022, StatPearls; Meek 2002b, BMJ; Samesima 2022, Arq Bras Cardiol

What does automaticity mean?

  • The ability of heart muscle to shorten when it is stimulated
  • The ability of heart cells to pass an impulse on to the next cell
  • The time when a cell cannot respond to a new impulse
  • The ability of certain heart cells to start an impulse on their own
Show the answer

Answer: The ability of certain heart cells to start an impulse on their own

Automaticity is the ability of specialized heart cells to depolarize spontaneously and start an impulse without any outside stimulus. The sinoatrial node normally has the highest built-in rate, so it leads.

Sources: Wei 2023, StatPearls; Rogoff 2022, StatPearls; Sattar 2023, StatPearls

On an EKG, what is artifact?

  • Deflections on the tracing that do not come from the heart’s electrical activity
  • An extra beat that starts in the ventricles
  • The normal change in heart rate with breathing
  • The calibration mark at the start of the tracing
Show the answer

Answer: Deflections on the tracing that do not come from the heart’s electrical activity

Artifact is anything on the tracing that does not come from the heart’s electrical activity. Common sources are movement, muscle tremor, electrical interference and loose electrodes.

Sources: Pérez-Riera 2018, Ann Noninvasive Electrocardiol; Open RN 2023, Nursing Advanced Skills; Kligfield 2007, Circulation