Sunset Calculator - Solar Sunset and Day Length

Our free sunset calculator determines the precise time the Sun disappears below the horizon for any location worldwide. This tool supports photographers planning golden hour shoots, hikers scheduling safe returns, and astronomers preparing for night observations. By entering coordinates and elevation, you get immediate solar estimations. Knowing the exact moment of dusk helps optimize schedules and prevents you from being caught in unexpected darkness.

• • Landscape Photography: Photographers use the sunset calculator to plan outdoor shoots and maximize the golden hour. Tracking rapid light changes ensures optimal exposure and composition.
• • Outdoor Safety: Hikers and climbers use sunset times to plan their return. Many trail accidents happen due to sudden visibility loss after dark, making sunset planning essential.
• • Astronomy Planning: Astronomers calculate sunset to determine when twilight begins. Knowing when civil, nautical, and astronomical twilight start helps plan telescope setup.
• • Solar Energy Diagnostics: Solar technicians analyze seasonal daylight patterns to evaluate solar panel productivity, predicting generation cycles and battery needs.

Calculating the exact moment of sunset requires understanding Earth's geometry. The Sun is not a point source, and light bends as it passes through the atmosphere. While standard calendars are general, precision activities require accounting for latitude, longitude, and elevation. Higher elevations expand the visible horizon, delaying sunset by letting observers see further along Earth's curve.

Our sunset calculator integrates elevation adjustments directly. By combining coordinates, elevation, and date, the tool provides a comprehensive overview of daily solar transit, allowing you to plan outdoor events with complete confidence.

To coordinate morning activities alongside your evening plans, our sunrise calculator provides the corresponding morning times for any location.

To calculate the sunset time, the calculator uses astronomical algorithms that determine the Sun's declination and the Equation of Time. These parameters are then combined with the observer's latitude, longitude, and height above sea level to solve the solar hour angle equations.

• Latitude (φ): The angular distance of a place north or south of the Earth's equator, ranging from -90° to 90°.
• Solar Declination (δ): The angle between the Sun's rays and the plane of the Earth's equator, which varies from -23.44° to 23.44° throughout the year.
• Equation of Time (EoT): An astronomical correction factor that accounts for the eccentricity of Earth's orbit and its axial tilt, causing solar noon to drift.
• Horizon Correction (h_c): An angular offset (usually 0.833° at sea level) that accounts for the Sun's physical semi-diameter (16 arcminutes) and atmospheric refraction (34 arcminutes).

The standard formula assumes a flat, sea-level horizon where the solar zenith angle is 90.833°. This includes a 34 arcminute correction for refraction and 16 arcminutes for the Sun's radius. According to the NOAA Global Monitoring Laboratory, solar calculations rely on Meeus algorithms to calculate declination and the equation of time.

Increased elevation delays sunset. The calculator applies a geometric adjustment to the zenith angle. Standing at 100 meters delays observed sunset by about 2 minutes compared to sea level because the visible horizon is pushed further away.

According to NOAA Global Monitoring Laboratory, solar calculations rely on algorithms from Astronomical Algorithms by Jean Meeus to calculate the Sun's declination and equation of time.

To view a complete daily breakdown of both morning and evening solar events on a single interface, our sunrise sunset calculator aggregates these calculations in one view.

Understanding the astronomical concepts behind sunset calculations makes it easier to interpret results and coordinate your outdoor activities.

These factors interact to produce unique day lengths. While equatorial regions experience stable sunset times, high-latitude locations see dramatic seasonal changes, ranging from midnight sun to polar night.

Modeling these behaviors mathematically allows us to predict solar events for any date and location. This allows educators and researchers to calculate solar parameters without physical measurements.

To analyze how the angle of the Sun changes during the day relative to the zenith, using the sun angle calculator offers detailed solar altitude and azimuth charts.

Follow these simple steps to estimate the precise sunset time for your coordinates and elevation using the sunset calculator.

1. 1 Enter Coordinates: Input your decimal latitude and longitude. Positive values represent the Northern and Eastern hemispheres.
2. 2 Specify Date: Select the year, month, and day. The calculator accounts for leap years automatically to maintain precision.
3. 3 Provide Timezone Offset: Enter your local timezone offset from UTC in hours (e.g. -4 for Eastern Daylight Time) to adjust output to local time.
4. 4 Add Elevation: Enter your altitude above sea level in meters. If you are at sea level or in a flat valley, leave this field at 0.
5. 5 Review Outputs: Click Calculate to view the local sunset, sunrise, solar noon, daylight duration, declination, and equation of time.

If you are planning a sunset hike on Mount Marcy in New York (latitude 44.1126° N, longitude -73.9647° W, elevation 1629 meters) on June 30, 2026, you would enter these values along with a timezone offset of -4. The calculator accounts for the elevation, showing that sunset occurs at 8:43 PM, which is about 8 minutes later than the surrounding valley. This helps you plan your descent time safely.

Integrating sunset calculations into your routine offers several practical benefits for safety, productivity, and planning.

• • Outdoor Safety: Anticipating when natural light will fade prevents wilderness emergencies. Planning hikes around exact sunset times ensures you are off the trail safely.
• • Photography: Knowing the precise timing of sunset allows you to capture the best natural lighting, arriving early to set up for the golden hour.
• • Energy Planning: Solar installers use day length trends to estimate power generation. Analyzing daylight hours helps plan backup battery needs.
• • Agricultural Scheduling: Farmers plan operations based on available daily light. Day length affects crop development, making seasonal tracking useful.

Calculating these times removes guesswork. Whether coordinating outdoor construction, planning flight operations, or arranging sporting events, having exact astronomical data ensures efficient operations.

Understanding day length variation also helps plan lighting systems for buildings and public areas, reducing energy consumption by aligning illumination with natural darkness.

Several atmospheric and geographic factors influence the accuracy of sunset calculations and can cause observed times to deviate slightly.

• • The calculator assumes a standard atmospheric refraction of 34 arcminutes, which varies with temperature and pressure.
• • Local terrain obstructions are not modeled. If you are in a valley, the physical sunset will occur earlier than calculated.

According to the US Naval Observatory, standard sunset times use a solar zenith angle of 90.833 degrees to account for refraction. Deviations from standard pressure can cause the actual sunset time to vary by up to 2 minutes.

For critical navigation, professional agencies use real-time meteorological observations. For everyday planning, photography, and hiking, standard astronomical models remain highly reliable.

According to US Naval Observatory Astronomical Applications Dept, standard sunrise and sunset times use a solar zenith angle of 90.833 degrees to account for standard atmospheric refraction at the horizon.

To study how observer height affects horizon distance and line-of-sight propagation geometries, the radar horizon calculator explains the mathematical formulas for horizon distance.