Sunrise Sunset Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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This page is best used as a focused physics model, experiment aid, or conceptual check rather than a black-box prediction. Sunrise Sunset Calculator connects its visible setup to sunrise and sunset estimate, making it easier to separate the governing relation from real-world effects that the page does not model.

What this calculator does

The Sunrise Sunset Calculator brings together Day of year, Hemisphere (N/S), Latitude (φ), Hemisphere (E/W), Longitude (λ) around the page’s sunrise and sunset estimate. The formula section below identifies which values actually drive that result and which fields are supporting or derived quantities, so you can check the page without assuming every visible box is an independent input.

How to use it

The main fields on this page are Day of year, Hemisphere (N/S), Latitude (φ), Hemisphere (E/W), Longitude (λ). Enter the quantities you actually know, keep their units consistent, and leave derived/output-style fields blank unless the formula explicitly allows solving in the opposite direction. For a clean check of sunrise and sunset estimate, change one driving quantity at a time and confirm that the result moves in the direction predicted by the equation.

How the calculation works

The intended solar model derives declination and hour angle from latitude and day of year to estimate daylight duration, sunrise, and sunset in solar time. The active legacy handler expects day_of_year, but the visible page uses a field named day.

Example

For example, start with the page’s populated scenario: Hemisphere (N/S) = N; Hemisphere (E/W) = E; Time zone = 0. Apply the equation above using the units shown on the page, then compare the calculated sunrise and sunset estimate with the displayed result. As a second check, change one physical input while holding the others fixed and confirm that the direction of change makes sense for this formula.

How to interpret the result

Interpret sunrise and sunset estimate within the idealized model described above. A useful answer should move in the direction predicted by the underlying physics when one driving quantity changes; if it does not, recheck units and the page’s field mapping before drawing a real-world conclusion.

Limitations and notes

The visible field is day, while the active handler looks for day_of_year. The model is also an approximate solar-time calculation and does not replace a location-aware ephemeris with refraction, elevation, and civil-time rules.