Sunrise Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Sunrise, sunset, and daylight are geometry problems wrapped in calendar and clock conventions. Sunrise Calculator estimates local sunrise time from the solar model used on this page, while separating astronomical geometry from local-horizon effects.

What this calculator does

The Sunrise Calculator centers on local sunrise time using the fields that are actually present here: Day date (MM/DD/YYYY), Hemisphere, Latitude (φ), Hemisphere, Longitude (λ). Rather than treating every box as an independent input, use the equation below to identify the driving quantities and read the remaining fields as derived or supporting values when appropriate.

How to use it

Enter a valid date, latitude with hemisphere, longitude with hemisphere, and the correct UTC offset for that date. The result is a local-clock sunrise estimate.

How the calculation works

The page uses a NOAA-style sunrise approximation from calendar day, latitude, longitude, and UTC offset. It solves the solar hour angle at a zenith of about 90.833°, a common correction that accounts approximately for atmospheric refraction and the Sun’s apparent radius near the horizon.

Example

For a mid-latitude location such as 40° N, 74° W near the June solstice, the model returns an early-morning local sunrise. Changing the UTC offset by +1 hour shifts the displayed clock time by about one hour without changing the underlying solar geometry.

How to interpret the result

Interpret the result as the model’s local-clock sunrise for the entered date, coordinates, and UTC offset. A time-zone change shifts the displayed clock time, while latitude and season change the solar geometry itself; compare nearby dates to see the seasonal trend rather than over-reading a single minute.

Limitations and notes

This is an astronomical approximation, not a terrain-aware local observation. Mountains, buildings, elevation, unusual refraction, weather, and the exact daylight-saving offset can move the observed time. Enter the date and UTC offset that actually apply to the location; the calculator does not infer time zone or daylight saving automatically.