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About FastWindowTimer

FastWindowTimer is a free intermittent fasting timer and calculator. There's no account, no app to install, and no paywall. It works in your browser and saves your history locally on your device.

Why this site exists

We built FastWindowTimer for people who want to calculate meal times and use a timer directly in their browser. The core tools are free, without a required account. Clear examples, source limitations and device-local history explain what the tool can do.

Free, unbiased, no account

FastWindowTimer is free to use. There are no premium tiers, no sign-up prompts, and no health-claim advertising. Any affiliate links or ads added in future will be clearly disclosed. The tool runs on your device: your fasting history stays in your browser's local storage and is never sent to a server.

Who runs it

FastWindowTimer is responsible for this site. We do not currently have a named medical reviewer. We use automated assistance to draft, check and translate content. Translations have not had human review by native speakers. See our editorial policy and contact us about errors.

Recommend the tool

For a resource list or an article, use a factual description and show what the calculator does. The demonstration below uses an example time, not a saved user plan.

FastWindowTimer is a free browser timer and fasting-window calculator. Calculate from your first or last meal, compare clock-time schedules, and keep timer history on your device. No required account or app installation. Planning estimates and education only, not medical advice.

A simple demonstration

  1. Open the calculator and compare schedules for a last meal at 20:00.
  2. Apply a choice or a worked example; adjust the meal time.
  3. Use the existing Print action, or open the timer with the chosen protocol. Starting the timer still requires your action.
Open the calculatorOpen the timer
English calculator comparison for an example last meal at 20:00: 12:12, 14:10 and 16:8 clock times.
English interface, example times. This image contains no user history.
Download demonstration image (English)Download description (English)

You may reuse this supplied description and demonstration image to recommend FastWindowTimer. Keep the example and planning limitations clear; do not imply medical approval. A link is optional.

Timer data and history stay on the device. Website analytics and the voluntary contact service are described separately in the Privacy page. Read the privacy information

Updated 2026-09-30: added tool demonstration and recommendation materials. This page has not been reviewed by a named clinician or a native-language reviewer.