What 4-7-8 breathing is
Inhale through the nose for four seconds, hold for seven, then exhale through the mouth for eight. One round takes nineteen seconds. There is no pause at the bottom — the next inhale follows the exhale directly.
The ratio is what matters, not the absolute numbers. The exhale is twice the length of the inhale, and the hold sits between them.
Why the long exhale works
Your heart rate rises slightly as you breathe in and falls as you breathe out. Making the exhale much longer than the inhale means you spend more time in the falling half of that cycle, and the effect compounds over a few rounds.
This is why 4-7-8 feels different from box breathing. It is not a focus tool. It is a downshift, and it works quickly enough that people notice it on the second or third round.
When to use it
At the end of the working day, before sleep, or in the middle of the kind of anxiety that makes it hard to think. Four rounds is the usual recommendation and takes a little over a minute.
It is a poor choice right before something demanding. If you need to be sharp, use box breathing instead.
If the seven-second hold is too long
Scale the whole pattern down while keeping the ratio: two in, three or four hold, four out. You will get the same downshift without the strain.
Most people find the hold, not the exhale, is the hard part at first. It gets easier within a week or so of regular practice.
Questions
How many rounds of 4-7-8 should I do?
Four rounds is the standard starting point, and that is what this timer runs. Building up to eight over a few weeks is fine, but there is little reason to go beyond that in one sitting.
Should I breathe out through my mouth?
Traditionally yes — a slow exhale through pursed lips, which naturally makes it longer. Through the nose works too if the mouth exhale feels forced.
Is 4-7-8 breathing safe?
For most people, yes, though the long hold makes lightheadedness more likely than with gentler patterns. Sit down, stop if you feel dizzy, and check with a clinician first if you are pregnant or have a heart or respiratory condition.