CPR Compression Depth and Rate: Getting the Numbers Right

Every chest compression you deliver during CPR is a direct pump to the heart. Push too shallow, and blood barely moves. Push too deep, and you risk breaking ribs without improving outcomes. Go too fast or too slow, and the heart never fills with enough blood to make the next compression count.

Book a hands-on CPR training session with CPR1 and practice compression depth and rate with real-time feedback from certified instructors.

The American Heart Association (AHA) has spent decades studying what separates effective CPR from ineffective CPR, and compression depth and rate sit at the center of those findings. This guide breaks down the exact numbers you need to know for adults, children, and infants, explains why those numbers matter, and covers the most common mistakes rescuers make under pressure.

What Are CPR Compression Depth and Rate?

CPR compression depth is how far you press down on the chest during each compression. CPR compression rate is how many compressions you deliver per minute. Both measurements work together to create enough blood flow to keep the brain and heart alive until advanced medical care arrives.

Think of it this way: depth controls how much blood each compression pushes out, and rate controls how often that blood gets pushed. If either number falls outside the recommended range, the quality of CPR drops, and so do the patient’s chances of survival.

The AHA’s 2025 Guidelines for CPR and Emergency Cardiovascular Care set specific targets for both depth and rate based on the patient’s age group. These numbers come from years of clinical research, manikin studies, and real-world cardiac arrest data.

AHA Guidelines for Compression Depth by Age Group

Compression depth is not one-size-fits-all. The AHA sets different targets for adults, children, and infants because chest size and rib flexibility vary by age. Here is a breakdown of the current guidelines.

For adults, the AHA updated its depth recommendation from “at least 2 inches” to a specific range of 2 to 2.4 inches. That upper limit exists because research shows compressions deeper than 2.4 inches increase the risk of rib fractures and internal injuries without improving blood flow.

For children and infants, the one-third-of-chest-depth guideline accounts for the wide range of body sizes within each age group. A 2-year-old and a 10-year-old both fall into the “child” category, but their chests are very different sizes. Using the one-third rule helps rescuers adjust on the fly. For more detail on depth by age, see our guide to CPR compression depth.

What Is the Correct CPR Compression Rate?

The correct CPR compression rate is 100 to 120 compressions per minute for all age groups, including adults, children, and infants. The AHA classifies this as a strong recommendation, and the same target applies whether you are performing one-rescuer or two-rescuer CPR.

This range was refined over several guideline cycles. Before 2010, the AHA recommended “approximately 100 compressions per minute.” The 2010 update changed the wording to “at least 100 per minute,” removing the upper limit. Then, the 2015 guidelines added the 120-per-minute ceiling after studies found that faster rates cause problems.

Research published in the journal Resuscitation found that compressions delivered at rates above 120 per minute led to decreased depth, incomplete chest recoil, and earlier rescuer fatigue. At 140 compressions per minute, systolic blood pressure dropped to 74% of baseline, and the percentage of compressions meeting quality standards dropped sharply.

On the other end, compression rates below 100 per minute are linked to lower rates of return of spontaneous circulation (ROSC). Studies comparing mean rates of 87 to 95 compressions per minute versus 40 to 72 per minute showed a 33% increase in ROSC with the higher rates.

How to Keep the Right Pace

Maintaining 100 to 120 compressions per minute is harder than it sounds, especially under stress. Here are some methods that work in real rescues and training sessions:

• Use a metronome app. Many free CPR metronome apps beep at 110 beats per minute, placing you in the center of the target range.
• Think of a familiar song. “Stayin’ Alive” by the Bee Gees has a tempo of about 104 beats per minute. “Crazy in Love” by Beyonce sits at about 100 BPM. Either song keeps you in range.
• Count aloud. Counting “one and two and three and four” at a steady pace helps maintain rhythm and lets bystanders assist with timing.
• Use a CPR feedback device. Many modern AEDs and training manikins include real-time feedback on compression rate and depth.

Train with CPR1’s certified instructors to build muscle memory for the correct compression rate and depth.

Why Depth and Rate Work Together

Compression depth and rate are not independent variables. Pushing deeper at the right speed generates the blood pressure needed to perfuse the brain and coronary arteries. Change one, and the other is affected.

A manikin study published in the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine found that the highest number of quality compressions (meeting both depth and recoil criteria) occurred at a rate of 120 per minute. At 100 per minute, fewer compressions met all quality benchmarks. But at rates above 120, depth started to suffer because rescuers could not push deep enough at that speed.

This trade-off is why the AHA sets both a floor and a ceiling for rate. Compressing at 150 per minute might feel like you are doing more, but each compression is shallower, less effective, and more likely to have incomplete recoil. The target is quality, not just speed.

Proper hand placement during CPR also affects your ability to reach the correct depth. Positioning your hands too high or too low on the sternum changes the mechanics of each compression and can reduce the blood flow generated.

Common Mistakes With Compression Depth and Rate

Even trained rescuers make errors during real cardiac arrests. Here are the most frequent compression mistakes and how to avoid them.

Compressing Too Shallow

This is the most common error. Studies consistently show that rescuers, especially those without recent training, compress too lightly. Fear of causing injury is the usual reason, but shallow compressions fail to generate enough blood flow. A compression of 1.5 inches on an adult is doing about half the work of a proper 2-inch compression.

Fix: Lock your elbows, keep your arms straight, and position your shoulders directly over your hands. Let your body weight do the work rather than relying on arm strength alone.

Compressing Too Deep

Going beyond 2.4 inches on an adult increases the chance of rib fractures, sternal fractures, and damage to internal organs. The 2015 AHA guidelines added the upper limit specifically to address this risk.

Fix: Practice on a feedback manikin that alerts you when compressions exceed the recommended depth. During a real rescue, focus on a controlled, consistent push rather than maximum force.

Compressing Too Fast

Adrenaline often pushes rescuers above 120 compressions per minute without them realizing it. The result is shallower compressions, incomplete chest recoil, and faster fatigue.

Fix: Count aloud or use a metronome. If you notice your rate climbing, take a deliberate breath between every few compressions to reset your rhythm.

Not Allowing Full Chest Recoil

Leaning on the chest between compressions prevents it from fully expanding. This reduces the amount of blood that refills the heart between pushes, cutting the effectiveness of the next compression.

Fix: Lift your hands slightly after each compression (without losing contact with the chest) to allow the chest to return to its natural position.

Pausing Too Long Between Compressions

Every pause in compressions drops coronary perfusion pressure. It can take 10 to 15 compressions to rebuild that pressure after a break. This connects directly to a concept called chest compression fraction, which measures the percentage of time during a cardiac arrest when compressions are being delivered.

Fix: Aim for a chest compression fraction above 60%, and ideally above 80%. Minimize interruptions for pulse checks, ventilations, and AED analysis.

Compression-to-Ventilation Ratios

The ratio of compressions to rescue breaths depends on the number of rescuers and the patient’s age.

Switching to a 15:2 ratio in two-person CPR for pediatric patients allows more ventilations per cycle, which matters because many pediatric cardiac arrests are caused by breathing problems rather than heart rhythm issues.

For rescuers unwilling or unable to give breaths, compression-only (hands-only) CPR is still effective for adults. Continuous compressions at 100 to 120 per minute without stopping to ventilate maintains some blood oxygen and is far better than no CPR at all.

Chest Compression Fraction and Why It Matters

Chest compression fraction (CCF) is the percentage of total resuscitation time spent actively compressing the chest. If a cardiac arrest lasts 10 minutes and compressions are delivered for 7 of those minutes, the CCF is 70%.

The AHA recommends a CCF of at least 60%, with a target above 80%. Every second without compressions allows coronary perfusion pressure to drop. Research shows that higher CCF values correlate with better survival rates.

Common compression fraction killers include:

• Extended pulse checks (limit to 10 seconds)
• Slow AED pad placement (apply while compressions continue when possible)
• Delayed rescuer switches (swap every 2 minutes, and do it in under 5 seconds)
• Stopping to give rescue breaths (each ventilation cycle should take no more than about 10 seconds for 2 breaths)

For a deeper look at CCF and how to improve it, read our article on chest compression fraction.

What Research Shows About Compression Quality and Survival

The link between compression quality and patient outcomes is well documented. Here is what the evidence says.

A study in the journal Circulation analyzing over 9,000 cardiac arrests found that patients who received compressions within the recommended depth range of 2 to 2.4 inches had significantly higher rates of ROSC compared to those who received shallower compressions. The same study confirmed that exceeding 2.4 inches did not further improve outcomes.

Data from the Resuscitation Outcomes Consortium showed that compression rates between 100 and 120 per minute were associated with the highest survival rates to hospital discharge. Rates below 100 and above 120 both showed lower survival.

A 2019 analysis in Resuscitation that included data from multiple countries found that high-quality CPR (correct depth, rate, recoil, and minimal interruptions) increased the odds of survival with favorable neurological outcomes by up to 50% compared to low-quality CPR.

These findings reinforce why training matters. Knowing the numbers is one thing. Delivering them consistently under pressure is another. Regular practice on feedback-enabled manikins helps rescuers build the muscle memory needed to perform high-quality compressions automatically.

Schedule CPR training with CPR1 to practice delivering high-quality compressions with certified instructors across all 50 states.

How to Recognize Signs of Cardiac Arrest and Begin CPR

Compression depth and rate only matter if you start CPR quickly. Recognizing cardiac arrest and beginning compressions within the first few minutes gives the patient the best chance of survival.

Look for these signs:

• The person suddenly collapses or becomes unresponsive
• No normal breathing (gasping or agonal breathing does not count as normal)
• No pulse (if you are trained to check, limit the check to 10 seconds)

Once you identify cardiac arrest, call 911 (or direct someone else to call), get an AED if one is nearby, and start chest compressions immediately. Place the heel of your hand on the center of the chest, interlock your other hand on top, and begin pushing hard and fast at a depth of 2 to 2.4 inches and a rate of 100 to 120 compressions per minute.

For infants under 1 year old, the technique changes. See our step-by-step guide on how to perform CPR on an infant for detailed instructions.

Frequently Asked Questions

What is the correct compression depth for CPR on an adult?

The correct compression depth for CPR on an adult is 2 to 2.4 inches (5 to 6 cm). This range is recommended by the American Heart Association to generate enough blood flow without increasing the risk of rib fractures or internal injury.

How fast should you do chest compressions during CPR?

You should deliver chest compressions at a rate of 100 to 120 compressions per minute. This applies to adults, children, and infants. Rates below 100 produce less blood flow, and rates above 120 reduce compression depth and chest recoil quality.

Is CPR compression depth the same for children and adults?

Not exactly. Adults need compressions of 2 to 2.4 inches deep. Children need compressions of about 2 inches (approximately one-third of the chest depth). Infants need compressions of about 1.5 inches (also roughly one-third of chest depth).

What happens if CPR compressions are too shallow?

Shallow compressions fail to generate enough pressure to push blood through the circulatory system. Studies show that compressions less than 2 inches deep on adults are associated with lower rates of return of spontaneous circulation and reduced survival.

Can you break ribs doing CPR?

Yes, rib fractures can occur during CPR, particularly in older adults. However, broken ribs are a recognized and accepted risk of effective chest compressions. The AHA’s recommended depth of 2 to 2.4 inches balances effectiveness with injury risk. Do not reduce compression depth out of fear of causing fractures.

What song matches the CPR compression rate?

“Stayin’ Alive” by the Bee Gees has a tempo of about 104 beats per minute, which falls within the recommended 100 to 120 range. Other songs near this tempo include “Crazy in Love” by Beyonce (about 100 BPM) and “Hips Don’t Lie” by Shakira (about 100 BPM).