Active Time Tools & Daylight

This category is the one place on WhenMath where a page keeps running rather than returning a single static answer, covering timers, stopwatches, and interval or focus-cycle tools. It also covers a related but different kind of question, the sun's position for a specific place and day, namely sunrise, sunset, solar noon, twilight windows, and how daylight duration changes across the year.

An active timer has to survive the browser tab, not just the math

A running timer has requirements a static calculation does not, such as staying accurate even when a background tab gets throttled, resuming correctly after an accidental refresh where the browser allows it, and offering pause, resume, and lap capture as real controls rather than a single start button. None of this is a notification feature. This site does not prompt for browser notification permission automatically.

Daylight is a location-and-date question, not just a date question

Sunrise and sunset depend on latitude and longitude, not only the calendar date, which is why the same date produces very different daylight durations in different places. These calculations use a location as a first-class input, and state clearly that they compute a standard geometric daylight window, not a guarantee of visible sunlight given local weather or terrain.

Where to go next

For a countdown to a fixed calendar date rather than a running timer, see Deadlines & Project Capacity. For converting a sunrise or sunset time into another time zone, see Time Zones & Meetings.

Active Time Tools & Daylight tools

• TimerA countdown timer that recomputes remaining time fresh, never incrementing.
• StopwatchMeasure elapsed time since start, recomputed fresh on every update.
• Interval TimerSequence named work/rest phases across repeated rounds.
• Pomodoro / Focus Cycle TimerSequence focus cycles with short breaks and a long break every few cycles.
• Countdown to Date TimerA live countdown to a specific date and time in a stated zone.
• Sunrise / Sunset CalculatorCalculate sunrise and sunset for a date and location using the NOAA solar equations.
• Daylight Duration CalculatorCalculate total daylight length (sunset minus sunrise) for a date and location.
• Solar Noon / Golden Hour CalculatorCalculate solar noon and the morning/evening golden-hour windows.
• Twilight Window CalculatorCalculate civil, nautical, and astronomical twilight windows.
• Daylight Change ComparatorCompare daylight duration between two dates/locations and see the signed change.
• Annual Sunlight PlannerCompare daylight duration and sunrise/sunset across several dates at one location.