The standard ratio of chest compressions to rescue breaths is 30:2 for adults, children, and infants when a single rescuer is performing CPR. That means 30 compressions followed by 2 breaths, repeated in cycles until help arrives. This ratio applies in most situations, but it changes based on the number of rescuers, the age of the person, and whether advanced medical equipment is being used.
Why the 30:2 Ratio Exists
The 30:2 ratio isn’t arbitrary. Every time you pause compressions to give breaths, blood pressure in the heart’s arteries drops significantly. Research from Purdue University found that a 5-second pause for ventilation after every 15 compressions (the old standard) reduced coronary perfusion pressure by roughly 50%. After each pause, it takes 5 to 10 compressions just to rebuild that pressure back to where it was. In some cases, the old 15:2 ratio allowed overall blood pressure to fall below the threshold needed for effective resuscitation.
Mathematical modeling showed that both oxygen delivery and blood flow peak at a ratio near 30:2. Switching from the older 15:2 ratio to a higher compression count improved oxygen delivery by 7 to 33 percent. The 30:2 ratio strikes the best balance: enough uninterrupted compressions to keep blood moving, with just enough breaths to supply oxygen.
Adult CPR: One Rescuer
For adults, push hard and fast on the center of the chest 30 times, then give 2 rescue breaths. Each compression should reach at least 2 inches deep at a rate of 100 to 120 compressions per minute. Each breath should be about one second long, just enough to make the chest visibly rise. Then immediately start the next round of 30 compressions. Continue this 30:2 cycle until emergency medical services take over.
Children and Infants: When the Ratio Changes
If you’re the only rescuer helping a child or infant, the ratio stays at 30:2. The technique changes (you use one or two hands for a child, two fingers just below the nipple line for an infant), but the compression-to-breath pattern is the same.
The ratio shifts when two trained rescuers are present. With two people performing CPR on a child or infant, the recommended ratio drops to 15:2. One person handles compressions while the other manages the airway and delivers breaths. Because children and infants are more likely to experience cardiac arrest from breathing problems rather than heart problems, ventilation plays a bigger role in their resuscitation. The 15:2 ratio delivers more breaths per minute, which matters when the underlying cause is respiratory.
Compression depth also differs by age. For children, compress to about 2 inches. For infants, compress to about 1.5 inches. The rate stays the same across all ages: 100 to 120 per minute.
Newborns: A Different Ratio Entirely
Newborn resuscitation follows its own protocol with a 3:1 ratio. If a newborn’s heart rate remains below 60 beats per minute after 30 to 60 seconds of effective ventilation, rescuers deliver 3 compressions coordinated with 1 breath every 2 seconds. That works out to 90 compressions and 30 breaths per minute. This ratio reflects the fact that newborn cardiac arrest is almost always caused by a breathing problem, so frequent ventilation is critical.
When You Can Skip Rescue Breaths
If you’re untrained in CPR or uncomfortable giving mouth-to-mouth, hands-only CPR (continuous chest compressions without rescue breaths) is a valid and effective option for adults who collapse suddenly. The American Heart Association has recommended compression-only CPR for untrained bystanders since 2008, and research supports it. A study published in HSR Proceedings in Intensive Care and Cardiovascular Anesthesia found that bystander compression-only CPR produced better outcomes than standard CPR for out-of-hospital cardiac arrest in adults.
There are important exceptions. Rescue breaths remain crucial for children, for drowning victims, and when more than about 4 minutes have passed since the arrest. In these situations, oxygen depletion is a bigger factor, and compressions alone won’t compensate.
Drowning and Respiratory Emergencies
Drowning is one scenario where breaths matter from the start. The American Red Cross recommends opening the airway and delivering 2 rescue breaths before beginning compressions, then continuing with the standard 30:2 cycle. For children and infants in a drowning situation with two trained rescuers present, the ratio shifts to 15:2. The priority here is getting air into the lungs quickly, since the arrest was caused by oxygen deprivation rather than a heart rhythm problem.
How the Ratio Changes With Advanced Equipment
Once emergency responders place an advanced airway (a tube secured in the throat), the compression-to-breath cycle disappears entirely. Compressions become continuous with no pauses, and breaths are delivered at a rate of 10 per minute, independent of the compression rhythm. This eliminates the perfusion pressure drops that come with pausing for breaths, which is why paramedics prioritize getting an airway device in place.
Quick Reference by Situation
- Adult, one rescuer: 30:2
- Adult, two rescuers: 30:2
- Child or infant, one rescuer: 30:2
- Child or infant, two rescuers: 15:2
- Newborn: 3:1
- Untrained bystander, adult victim: compressions only, no breaths
- Advanced airway in place: continuous compressions, 10 breaths per minute (no fixed ratio)
Regardless of the ratio, the quality of compressions matters more than anything else. Push to the correct depth, allow full chest recoil between compressions, keep interruptions as short as possible, and maintain a rate of 100 to 120 per minute. A perfectly timed ratio means little if the compressions aren’t generating enough blood flow.