What is the Compression to Breath Ratio for Adult CPR in Australia?

The compression to breath ratio for adult CPR in Australia is 30 compressions to 2 rescue breaths, written as 30:2. The ratio comes from the Australian and New Zealand Resuscitation Council (ANZCOR) guidelines, which every accredited CPR course in Australia, including HLTAID009 Provide CPR, is built around.

Thirty compressions, then two breaths, then straight back to compressions — that is the rhythm you fall into when an adult is unresponsive and not breathing normally. This guide explains how the ratio works, how fast and deep to press, what changes for children and extra rescuers, and how training turns the numbers into muscle memory. ALIT runs HLTAID009 as a 3.5 hour on-campus course at West Melbourne with weekly intakes — see the HLTAID009 Provide CPR course page for upcoming dates.

What 30:2 looks like in practice

Start with compressions. Place the heel of your hand on the centre of the adult’s chest, put your other hand on top, and press straight down. Give thirty compressions, then open the airway and give two rescue breaths, each lasting about one second, watching for the chest to rise. Return your hands to the chest immediately and start the next thirty. Aim to complete about five cycles of 30:2 in roughly two minutes, and keep going until the ambulance arrives, an automated external defibrillator (AED) is ready to use, or the person shows clear signs of life.

The ratio is only one part of the pattern. Compressions should travel at a rate of 100 to 120 per minute and push down at least five centimetres for an average adult. Let the chest rise fully between compressions, because that recoil is what lets the heart refill. Minimise every pause: each second the chest is idle, the pressure the compressions have built starts bleeding away.

Why the ratio is 30:2 and not something else

Chest compressions work by squeezing the heart between the breastbone and the spine, creating enough pressure to push oxygenated blood to the brain. That pressure takes a run of compressions to build, and it drops almost as soon as you stop. A run of thirty gives the heart a decent stretch of pressure before the short pause for two breaths. International resuscitation evidence reviews compared the options and landed on 30:2 for adults as the balance that keeps blood moving longest without starving the brain of oxygen, and ANZCOR adopts that ratio in its CPR guideline for Australia and New Zealand.

Rate and depth matter as much as the count

A perfect 30:2 delivered too slowly or too shallowly does not circulate blood. The 100 to 120 compressions per minute rate is deliberately brisk — trainers often use the beat of a well-known disco song to make the tempo stick. At least five centimetres of depth is what an adult chest needs for the heart to be squeezed effectively. Full recoil between compressions matters just as much as the push, because leaning on the chest stops the heart refilling. If you have trained before and want to check your sequence end to end, ALIT’s refresher on the steps of CPR for adults walks through them one by one.

What changes for children and infants?

For adults the ratio is 30:2 in every case. For children and infants, a lone rescuer also uses 30:2, but when two or more trained rescuers are present the paediatric guidelines shift to 15 compressions to 2 breaths, because young bodies need proportionally more frequent breaths. Compression depth also changes — about one third of the chest depth, pressed with one or two hands for a child and two fingers for an infant. Those differences are exactly why CPR courses rehearse adult, child and infant manikins separately: you learn all three patterns together so you never have to work out which case you are in on the worst day of someone’s life.

Do you have to give breaths at all?

If you are unwilling or unable to give rescue breaths — for example, you are untrained, or you have no barrier device and are not comfortable — compression-only CPR is formally supported by the guidelines as far better than doing nothing. Hands-only CPR at 100 to 120 per minute keeps pushing the oxygen already in the blood around the body and buys time until an ambulance arrives. Trained rescuers should give the full 30:2 pattern where they can, but nobody should hesitate to start compressions because they feel unsure about the breaths.

Where 30:2 fits in the DRSABCD flow

The ratio sits inside a larger sequence. Danger is checked first, then Response; if there is no response you Send for help — call 000 and ask for an AED — then check Airway and Breathing. If the person is not breathing normally, compressions begin at the C step, at 30:2, and the Defibrillator is used the moment it arrives. The whole flow is covered in ALIT’s guide to the DRSABCD action plan, and every HLTAID009 course rehearses the full sequence, not just the chest work.

How training drills the pattern in

Reading a ratio is not the same as performing it. On a manikin you discover how deep five centimetres actually is, how tired your arms get by minute two, and how easily you drift below 100 per minute as fatigue sets in. Assessment requires you to demonstrate the pattern on adult, child and infant manikins, use an AED trainer and answer scenario questions about when to start and stop. ALIT’s guide on what a CPR course includes walks through the whole session so there are no surprises on the day.

Keeping the rhythm under pressure

Resuscitation skills decay quickly, which is why the Australian Resuscitation Council recommends refreshing CPR every twelve months even though the statement of attainment itself has no legislated expiry date. When you redo the course you relearn the ratio, the rate and the depth as one integrated pattern — and the manikin tells you honestly whether your compressions still pass. ALIT’s guide on how often CPR training should be renewed explains how the twelve-month cycle is applied by employers, placement providers and regulators.

FAQ

What is the compression to breath ratio for adult CPR in Australia?

Thirty compressions to two breaths (30:2), per the ANZCOR guidelines that underpin HLTAID009 and all accredited CPR training in Australia.

How fast should the thirty compressions go?

At a rate of 100 to 120 compressions per minute, pushing at least five centimetres deep and allowing the chest to rise fully between compressions.

Is the ratio different for children and infants?

A lone rescuer uses 30:2 for all ages. With two or more trained rescuers, children and infants move to 15 compressions to 2 breaths.

Can I just do compressions?

Yes. If you are unable or unwilling to give rescue breaths, compression-only CPR at 100 to 120 per minute is supported by the guidelines and is far better than no CPR at all.

How many cycles of 30:2 should I aim for in two minutes?

About five cycles, which is roughly two minutes of continuous CPR before reassessing or swapping compressors.

Where can I learn adult CPR in Melbourne?

ALIT delivers HLTAID009 Provide CPR as a 3.5 hour on-campus course at West Melbourne, with weekly intakes.