A solar-aware calendar view that shows why a fixed clock routine can feel different across the year, and how sunrise or sunset anchors change that schedule.
Use the instrument above, then check the calculation record, assumptions and related tools below.
Dynamic solar windows
Starts at 06:38, which is tied to sunrise for the selected day.
Starts at 16:55, held before sunset instead of drifting into darkness.
In 2026, the fixed wake time is before sunrise on 18 mornings and the fixed wind-down is after sunset on 251 evenings.
Method
The tool uses standard solar-position equations to estimate sunrise, sunset, daylight length and noon sun height for a latitude, longitude, UTC offset and year. It does not use weather, terrain, buildings, horizon obstruction or personal calendar data.
Location, time-zone offset, year, morning minutes after sunrise, evening minutes before sunset and fixed clock comparison times.
Compute solar declination and equation of time, solve the sunrise/sunset hour angle, then add routine offsets to the resulting local solar events.
Use official almanacs, weather data, local terrain checks or astronomy-grade software when precise observation or safety planning matters.