Sunrise Sunset Calculator
Sunrise Is Defined by an Angle, Not a Feeling
"Sunrise" has a precise technical definition: the moment the Sun's upper edge crosses the horizon, corrected for atmospheric refraction, which bends sunlight enough that the Sun is still geometrically about half a degree below the horizon when it visually appears to touch it. Getting the exact time right requires the Sun's position on that specific date (its declination, which shifts through the year) combined with the observer's exact location. This calculator runs that full calculation rather than relying on a generic seasonal estimate.
The Formula
Sunrise = Solar Noon − Hour Angle
Sunset = Solar Noon + Hour Angle
Solar declination and the equation of time (the small, date-dependent offset between clock time and true solar time) are computed first from the date using standard low-precision solar-position formulas, then combined with latitude to solve for the hour angle — how far, in time, sunrise and sunset sit from local solar noon.
Where This Matters
- Photography — golden hour and blue hour planning both start from knowing the exact sunrise or sunset time for a specific date and location.
- Solar energy — estimating daily sunlight hours for a solar installation depends on accurate sunrise/sunset times across the year, not just a rough average.
- Religious and cultural observance — many practices (prayer times, fasting windows) are tied directly to sunrise or sunset at a specific location.
- Outdoor event planning — anything from a wedding to a hiking trip benefits from knowing exactly how much daylight is available.
Standard Sun-Angle Reference Points
The 0.833° below-horizon threshold used for sunrise and sunset is one of several standard solar angle definitions used in astronomy and navigation:
| Sun's angle below horizon | Event |
|---|---|
| 0.833° | Sunrise / sunset (accounts for atmospheric refraction and solar disk radius) |
| 6° | Civil twilight ends/begins — outdoor activity generally needs artificial light beyond this point |
| 12° | Nautical twilight ends/begins — horizon no longer visible at sea |
| 18° | Astronomical twilight ends/begins — sky is fully dark for observation purposes |
These depression-angle definitions are standard, widely published astronomical conventions. Computed sunrise/sunset times from this calculator are accurate to roughly ±1–2 minutes and do not account for local horizon obstructions like mountains or buildings.
How to Use This Calculator
- Enter the date you want sunrise and sunset for.
- Enter the location's latitude (−90 to 90).
- Enter the location's longitude (−180 to 180).
- Enter the location's UTC timezone offset (for example, −5 for U.S. Eastern Standard Time).
- Select Calculate to get sunrise, sunset, and total day length.
Related Calculations
Pair this with the Moon Phase Calculator to know how dark the sky will actually be after sunset on a given night.