What is box breathing?
Box breathing is a four-step pacing technique: breathe in, hold, breathe out, hold — each for the same count. It's used by Navy SEALs, athletes, and anyone who needs to settle a racing nervous system in a couple of minutes. Watching the box expand and contract gives the rhythm a visual anchor so you don't have to count out loud.
Three other patterns are included. 4-7-8 (Andrew Weil) is a longer exhale that's good before sleep. Coherent breathing (5-in / 5-out, no holds) lands at six breaths per minute, the rate associated with peak heart-rate variability. Custom lets you set your own seconds.
Tips and shortcuts
Sit upright, jaw loose, shoulders down. Breathe through your nose if you can. The first cycle always feels too long — that's normal. Aim for five to ten cycles.
Shortcuts: Space start / pause · Esc stop · 1–4 switch pattern · S toggle sound.
The screen stays awake while a session is running (where supported). Your last pattern, sound preference, and a lifetime cycle counter are saved locally — nothing leaves your browser.
Not medical advice
This is a breathing pacer, not a medical device. If you have a heart, lung, or anxiety condition, or if breath-holds make you dizzy, talk to a clinician before using paced-breathing techniques. Stop if you feel light-headed.