How to Use Sunrise Sunset Calculator
The Sunrise Sunset Calculator delivers instant solar times for any location on Earth.
- Choose a Location Preset — Select a city from the preset list; the Sunrise Sunset Calculator fills in latitude, longitude, and UTC offset automatically.
- Enter Custom Coordinates — For unlisted locations, type latitude (−90 to 90) and longitude (−180 to 180) directly and choose the matching UTC offset.
- Pick a Date — Use the date picker or click the Previous/Next buttons to step through days; the Sunrise Sunset Calculator updates all results instantly.
The Sunrise Sunset Calculator outputs sunrise time, solar noon, sunset time, day length, and night length in local time based on the UTC offset provided. Click Show Golden Hour & Twilight to also view golden hour windows, blue hour windows, and civil, nautical, and astronomical twilight times.
Formula & Theory — Sunrise Sunset Calculator
The Sunrise Sunset Calculator implements a simplified NOAA solar geometry algorithm:
Solar Declination: δ = arcsin(sin(ε) · sin(λ))
Hour Angle: H = arccos((cos(90.833°) − sin(φ)·sin(δ)) / (cos(φ)·cos(δ)))
Solar Noon: t_noon = (720 − 4·lon − EoT + UTC_offset) / 60
Sunrise: t_rise = t_noon − H/15
Sunset: t_set = t_noon + H/15
Day Length: D = 2·H/15 (hours)| Symbol | Meaning |
|---|---|
| φ | Observer latitude (degrees) |
| λ | Solar ecliptic longitude |
| ε | Earth’s obliquity (~23.44°) |
| EoT | Equation of Time (minutes) |
| H | Hour angle at sunrise/sunset |
The 90.833° zenith accounts for atmospheric refraction and the sun’s apparent diameter, giving the Sunrise Sunset Calculator realistic civil sunrise/sunset times.
For the advanced twilight times, the Sunrise Sunset Calculator computes the hour angle at each altitude threshold:
| Event | Sun Altitude | Zenith Angle |
|---|---|---|
| Standard Sunrise/Sunset | −0.833° | 90.833° |
| Golden Hour end/start | +6° | 84° |
| Blue Hour boundary | −4° | 94° |
| Civil Twilight | −6° | 96° |
| Nautical Twilight | −12° | 102° |
| Astronomical Twilight | −18° | 108° |
Golden Hour is when the sun is between 0° and 6° above the horizon — the warm, soft light favored by photographers. Blue Hour is when the sun is between −4° and −6°, producing deep blue tones before sunrise and after sunset. Civil, nautical, and astronomical twilight define progressively darker stages of dawn and dusk.
Polar Conditions
When cos(H) < −1, the sun never dips below the horizon (midnight sun). When cos(H) > 1, the sun never rises (polar night). The Sunrise Sunset Calculator identifies both conditions automatically.
Use Cases for Sunrise Sunset Calculator
The Sunrise Sunset Calculator is useful across many disciplines and hobbies:
- Travel Planning — Look up sunrise and sunset times at your destination before arriving, so you can schedule sightseeing around the best natural light.
- Photography Golden Hour — Photographers rely on the Sunrise Sunset Calculator to plan shoots during the golden hour just after sunrise or just before sunset for warm, directional light.
- Outdoor Activities — Hikers, runners, and cyclists use the Sunrise Sunset Calculator to ensure they finish their routes before darkness falls.
- Agriculture and Gardening — Farmers and gardeners track day length across seasons to time planting, harvesting, and greenhouse supplemental lighting.
- Religious Observance — Many religious practices (fasting, prayer times, Shabbat) are tied to sunrise and sunset; the Sunrise Sunset Calculator provides precise local times.
- Education and Geography — Students use the Sunrise Sunset Calculator to observe how day length changes with latitude and season, illustrating Earth’s axial tilt and orbital mechanics.
- Energy Management — Solar panel operators use the Sunrise Sunset Calculator to predict peak generation hours and schedule battery storage accordingly.