Sunset Calculator

Select Date:


Latitude:


Longitude:


Calculate

The Sunset Calculator is a practical tool used by travelers, photographers, hikers, gardeners, and astronomy enthusiasts to determine when the sun will set at a specific location on a given day. Knowing the exact time of sunset allows you to plan your activities effectively, especially in scenarios where natural light is important.

Whether you’re capturing the perfect golden hour photograph, timing a beach picnic, or adjusting your solar-powered devices, a sunset calculator ensures you don’t miss nature’s final show of the day.

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Formula

To calculate the sunset time, the following steps and formulas are used:

1. Calculate the day of the year (N)
   N = the number of days since January 1st.
2. Approximate time of sunset (T):
   T = N + ((18 – LngHour) / 24)
3. Sun’s mean anomaly (M):
   M = (0.9856 × T) − 3.289
4. Sun’s true longitude (L):
   L = M + (1.916 × sin(M)) + (0.020 × sin(2M)) + 282.634
5. Right Ascension (RA):
   RA = atan(0.91764 × tan(L))
6. Sun’s declination (sinDec):
   sinDec = 0.39782 × sin(L)
7. Hour angle (H):
   cosH = (cos(zenith) − (sinDec × sin(lat))) / (cosDec × cos(lat))
8. Local mean time of sunset:
   T = H + RA − (0.06571 × T) − 6.622
9. UTC Time of Sunset:
   UT = T − LngHour

Note: Zenith = 90.833 degrees is used for standard sunset calculation.

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How to Use the Sunset Calculator

Using the sunset calculator is straightforward:

1. Enter the date for which you want the sunset time.
2. Enter your latitude and longitude.
3. Click the Calculate button.
4. The result will show the sunset time in UTC.

💡 Use a time zone converter to convert UTC to your local time zone.

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Example Use Cases

Let’s say you want to check the sunset for:

• New York City (latitude 40.7128, longitude -74.0060)
• Date: August 1, 2025

Enter the values in the calculator, and it will display the UTC sunset time (which you can convert to local time by subtracting 4 or 5 hours depending on daylight saving time).

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Real-World Applications

• 📸 Photographers use it to catch golden hour.
• 🏕️ Campers and hikers use it to return before dark.
• 🧘‍♀️ Yoga instructors time outdoor sessions at sunset.
• 🛰️ Astronomers and stargazers prepare for dark sky observation.
• 🌞 Solar panel installers assess energy windows.
• 🕰️ Websites and apps use it to update themes or lighting modes.

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FAQs – Sunset Calculator

1. What is a sunset calculator?
A sunset calculator tells you the time the sun will set at a specific latitude, longitude, and date.

2. Is sunset time the same every day?
No, it changes daily depending on Earth’s tilt and your geographic location.

3. What is UTC in the result?
UTC stands for Coordinated Universal Time. You need to convert it to your local time zone.

4. What does 90.833 mean in the formula?
It represents the solar zenith angle used for official sunset time.

5. Can I use this for sunrise?
This specific tool is for sunset. The sunrise calculation is similar but uses a different hour angle.

6. Is the result accurate?
Yes, it uses standard astronomical formulas and is accurate to within a few minutes.

7. What if I enter incorrect latitude/longitude?
The calculator may return an error or an unrealistic sunset time. Ensure your values are valid.

8. How do I get my location’s coordinates?
Use Google Maps or a GPS app to find your exact latitude and longitude.

9. Can I use this without internet?
Yes, the calculator runs in your browser using JavaScript.

10. Why is my sunset time different than Google’s?
Google often adjusts for local elevation, time zones, and atmospheric conditions. This tool provides a clean astronomical estimate.

11. Do seasons affect sunset time?
Yes. Sunset times vary widely between summer and winter due to Earth’s axial tilt.

12. Is elevation considered?
No. This calculator assumes sea-level calculations. High elevations may see the sun set later.

13. Can this be used anywhere in the world?
Yes. As long as latitude and longitude are valid, it works globally.

14. How often does sunset time change?
Sunset can shift by 1–2 minutes daily, depending on time of year and location.

15. Does daylight saving time affect results?
The calculator provides UTC time. You need to adjust it for daylight saving manually.

16. Can this tool help solar panel planning?
Yes, it can help identify how many daylight hours you’ll have per day.

17. Is there a mobile version of this calculator?
This version is mobile-friendly. You can also embed it into your app or site.

18. How do I convert UTC to my time?
Subtract or add the time difference between your time zone and UTC. Tools like timeanddate.com can help.

19. What happens near the poles?
Sunset and sunrise calculations may break down during polar day/night periods.

20. Can this be used for religious observances?
Yes, many users use sunset calculators for prayer times, fasting schedules, and cultural rituals.

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Conclusion

The Sunset Calculator is a powerful and accurate tool that serves a wide range of users. Whether you’re timing your outdoor activities, capturing the sunset in a photo, or calculating solar energy hours, knowing when the sun will set helps you plan better.