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How and When to Do CPR

Hands-Only CPR for adults, how it changes for children and infants, and how to use an AED.

Last reviewed October 3, 2026 · Spiral Search editorial team

Call 911 first and put the phone on speaker. The dispatcher will guide you. If you are alone and an AED is within reach, get it, but do not delay chest compressions.

General information, not medical advice. Reading a guide is not a substitute for a hands-on first aid or CPR class (American Red Cross, American Heart Association, and local fire-rescue departments offer them). If someone may be in danger, call 911 and follow the dispatcher.

When to start CPR

Start CPR if a person is unresponsive and not breathing, or only gasping. Gasping is not normal breathing. If you are unsure, start. It is always better to try than to do nothing.

Hands-Only CPR for adults (untrained or unsure)

Make sure the scene is safe. Tap the person and shout. Check for normal breathing for no more than 10 seconds.
Call 911 and place the person on their back on a firm surface.
Put the heel of one hand on the center of the chest, the other hand on top.
Keep your shoulders over your hands and your elbows locked.
Push hard and fast: at least 2 inches deep, 100 to 120 times a minute. Let the chest come all the way back up between pushes.
Do not stop until emergency responders arrive, an AED tells you to stop, the person moves, or you are too exhausted to continue.

Tip: A pace of 100 to 120 per minute matches the beat of many popular songs. Switch rescuers every two minutes if more than one person is present.

If you are trained: compressions and breaths

If you are trained in CPR, use 30 compressions followed by 2 rescue breaths, each breath lasting about one second. Tilt the head back, lift the chin, pinch the nose and seal your mouth over theirs. If the chest does not rise, re-tilt and try once more. Avoid tilting the head if you suspect a neck injury.

Children and infants

	Adult	Child (1 year to puberty)	Infant (under 1 year)
Hand position	Two hands, center of chest	One or two hands	Two fingers, just below the nipple line
Depth	At least 2 inches	About 2 inches	About 1.5 inches
Rate	100–120 per minute	100–120 per minute	100–120 per minute
Cycle	30:2 if trained	30:2 if trained	30:2 if trained

In children and infants, breathing problems are a common cause of cardiac arrest, so breaths matter more. If you are alone with a child or infant who is not breathing, give about 2 minutes of CPR first, then call 911 if no one else has.

Using an AED

Turn it on and follow the voice prompts.
Bare the chest and stick the pads exactly as the picture shows. Use child pads or the child setting for children under 8 if available; otherwise use adult pads.
Make sure nobody is touching the person while it analyzes.
If it advises a shock, shout “clear,” check that nobody is touching the person, and press the button.
Resume compressions straight away.

Modern AEDs are safe for bystanders. They will not shock someone who does not need it.

Choking is different

If a person is conscious and cannot cough, speak or breathe, call 911 and give back blows and abdominal thrusts as taught in a first aid class. If they become unresponsive, start CPR.