About the Breathing Exercise Timer
A free, browser-based breathing timer with an animated circle pacer, audio cues, and guided sessions for box breathing, 4-7-8, and Wim Hof–style rounds.
What it is
The Breathing Exercise Timer guides you through structured breathing sessions entirely in your browser. Choose a technique, set your phase durations and number of rounds, then press Start. A circle on screen expands as you inhale and contracts as you exhale, with a phase label and countdown always visible so you never lose your place. Soft audio cues mark each transition so you can close your eyes and follow the rhythm without watching the screen.
Three techniques are included: box breathing (4-4-4-4), the 4-7-8 relaxation pattern, and Wim Hof–style rounds with configurable rapid-breath cycles followed by retention and recovery holds. All phase durations and round counts are adjustable. Settings lock while a session runs to prevent accidental changes.
Everything runs locally in your browser. No data is sent to a server, stored, or logged.
The techniques
Box Breathing (4-4-4-4)
Four equal phases: inhale for 4 seconds, hold for 4, exhale for 4, hold for 4. The symmetrical structure steadies the breath and the nervous system, and is widely used by athletes, military personnel, and anyone who needs to focus quickly or reduce acute stress. All four durations are adjustable; the classic 4-4-4-4 is the default.
4-7-8 Breathing
Inhale for 4 seconds, hold for 7, exhale for 8. The long exhale relative to the inhale activates the parasympathetic nervous system, making 4-7-8 a popular technique for winding down before sleep or calming stress quickly. All three phase lengths are adjustable from the default values.
Wim Hof Style
A round consists of a configurable number of rapid deep breaths (default 30, each 2 s inhale + 2 s exhale), followed by a retention hold on the exhale (default 60 s) and a recovery inhale hold (default 15 s). The rapid breathing hyperventilates the body; the hold phases are said to increase CO₂ tolerance. This technique carries real risk — see the safety section below.
Key features
Animated circle pacer
A circle smoothly expands over the duration of each inhale phase and contracts over each exhale, giving an intuitive visual cue that matches the rhythm of your breath. The circle holds at full or empty size during hold phases. Phase colour shifts between inhale (blue) and exhale (green) to reinforce the transition.
Audio cues via Web Audio API
Soft tones mark every phase transition — a gentle rising tone for inhale, a falling tone for exhale, a neutral bell for hold phases, and a three-note chime at session end. Generated via the Web Audio API so they play reliably even when the tab is backgrounded or the screen locked.
Screen Wake Lock
On supported browsers the timer requests a screen wake lock on Start so the display stays on throughout your session. The lock is released when you pause, reset, or the session ends. On unsupported browsers the timer and audio cues still work normally.
Adjustable settings
Each technique has its own settings panel. Box breathing and 4-7-8 expose individual phase durations in seconds plus a round count. Wim Hof exposes breath count, inhale/exhale speed, retention hold length, recovery hold length, and round count. Settings lock while running to prevent accidental changes.
Wim Hof safety — important
Wim Hof–style breathing combines rapid breathing (which lowers CO₂) with extended breath holds. Reduced CO₂ can cause dizziness, light-headedness, tingling, muscle contractions, or loss of consciousness. This can happen without warning. To practise safely:
- Never practise in or near water — drowning risk if you lose consciousness.
- Never practise while driving or operating machinery.
- Always sit or lie down on a surface from which you cannot fall.
- Stop immediately if you feel dizzy, confused, or unwell.
- Do not practise if you are pregnant or have heart, respiratory, seizure, or other medical conditions without first consulting a physician.
The timer requires you to read and acknowledge this warning before starting a Wim Hof session.
This tool is a general breathing guide and is not medical advice. Box breathing and 4-7-8 breathing are gentle techniques suitable for most people, but consult a physician if you have any health concerns before starting a new breathing practice. Wim Hof–style breathing involves rapid breathing and extended breath holds that can cause dizziness, light-headedness, or loss of consciousness — never practise it in or near water, while driving, or while standing; always sit or lie down in a safe place and stop immediately if you feel dizzy or unwell. Avoid Wim Hof-style breathing if you are pregnant or have heart, respiratory, seizure, or other medical conditions without first consulting a physician.
Who it's for
Wind-down before sleep
The 4-7-8 pattern is popular specifically as a pre-sleep ritual. Select it, set 4–8 rounds, and let the pacer guide you down.
Focus and stress relief
Box breathing is used by athletes and professionals before high-pressure moments. A few rounds can clear mental noise quickly.
Mindful breaks
Even a single round of box breathing takes under 2 minutes and can reset your attention and lower perceived stress mid-day.
Wim Hof practice
For those already familiar with the Wim Hof method who want a structured timer with an animated pacer and audio cues, with the safety acknowledgment built in.