Active Time Tools & Daylight

This category is the one place on WhenMath where a page keeps running rather than returning a single static answer: 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: 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: 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.