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Free intermittent fasting timer

Start a 16:8 timer and track elapsed time and your planned eating window. No download or sign-up; history stays in this browser. Phase labels are educational, not body measurements.

  • No app
  • No account
  • Local history
  • Works offline
Timer not running00:00:00

Free, no account, no app. Your timer and history stay in this browser.

  1. Fed
  2. Early fasting
  3. Fuel-use context
  4. Ketone context
  5. Longer fasting
Your on-device data

Back up, restore, or erase the timer data stored in this browser. Nothing is sent to a server.

Planning estimates only — see methodology for phase sources. Not medical advice.

How the fasting timer works

Choose a schedule, start the timer, and track elapsed and remaining time. The phase timeline uses illustrative hour markers; a clock cannot measure your insulin, ketones or autophagy.

  1. Pick a protocol

    Compare eating windows with your actual meal times. A schedule label does not establish medical suitability.

  2. Start with one tap

    The timer runs right in this browser — no download, no account. Your session and history stay on this device.

  3. Track time, understand the limits

    See elapsed time and educational reference markers. End or adjust the fast whenever needed; completing a longer window is not a health requirement.

Educational fasting timeline

  • Fed

    reference marker: 0h

  • Early fasting

    reference marker: 4h

  • Fuel-use context

    reference marker: 12h

  • Ketone context

    reference marker: 16h

  • Longer fasting

    reference marker: 24h

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