A guided box breathing timer
Box breathing divides each breath into four equal phases — inhale, hold, exhale, hold — to slow the breath and calm the mind. This timer paces you through the rhythm with a clear prompt and an animated square that expands as you breathe in and contracts as you breathe out.
The physiology behind the technique
Controlled breathing at a slow, even rate activates the parasympathetic nervous system — the body’s “rest and digest” response. By holding after both the inhale and the exhale, box breathing creates a brief, rhythmic pause that slows the heart rate and reduces cortisol activity. US Navy SEALs popularised the technique for managing stress in high-pressure environments; it is also used in clinical settings to manage anxiety. The four-phase equal structure makes it easy to learn because there are no fractions or differing phase lengths to remember.
How it works
You pick the seconds per phase (3, 4, 5 or 6). When you press Start, the timer counts down each phase and automatically advances to the next: Breathe in → Hold → Breathe out → Hold, then loops. Each time it returns to the first phase it counts one completed cycle. The square scales smoothly over your chosen duration so you can follow the pace by eye instead of counting.
Phase timing at each setting
| Phase | 3-second box | 4-second box | 5-second box | 6-second box |
|---|---|---|---|---|
| Inhale | 3 s | 4 s | 5 s | 6 s |
| Hold in | 3 s | 4 s | 5 s | 6 s |
| Exhale | 3 s | 4 s | 5 s | 6 s |
| Hold out | 3 s | 4 s | 5 s | 6 s |
| Cycle total | 12 s | 16 s | 20 s | 24 s |
| 10 cycles | ~2 min | ~2:40 | ~3:20 | ~4 min |
The 4-second setting is the classic starting point. Begin with 3 seconds if you find it difficult to hold comfortably at first, and work up to 5 or 6 seconds as your breath control improves.
When to use it
- Before a stressful event: Run through 5–10 cycles before a presentation, difficult conversation, or any high-pressure situation where you need to stay clear-headed.
- After an adrenaline spike: If you feel your heart rate surge from unexpected stress, a few cycles of box breathing can bring it back toward baseline quickly.
- At the start or end of a work session: Using a brief breathing routine as a transition ritual helps the mind shift between contexts — particularly useful when working from home where physical transitions between spaces are absent.
- Falling asleep: A slower 5- or 6-second box is a widely recommended wind-down technique that activates the parasympathetic response without requiring effort or distraction.
The timer records nothing — no breathing or health data is collected or uploaded.