Sunset Calculator

About the Sunset Calculator

Sunset is just the beginning of evening — after the sun dips below the horizon, twilight unfolds in three phases. Civil twilight (sun 0-6° below) provides enough light for outdoor activities. Nautical twilight (6-12°) allows navigation by the horizon. Astronomical twilight (12-18°) is when the sky is dark enough for telescopes. True night begins only when the sun is more than 18° below the horizon.

For photographers, the golden hour — roughly the last hour before sunset — offers warm, directional light ideal for portraits and landscapes. The blue hour follows immediately after, bathing scenes in cool, diffuse blue tones. Planning these windows requires knowing the exact sunset time and twilight progression.

Sunset times vary dramatically with latitude and season. At the equator, sunset shifts by only about 30 minutes year-round. At 50°N, it ranges from 4:00 PM in December to 9:30 PM in June. It gives complete sunset and twilight data for any location on Earth, with a monthly comparison table for seasonal planning.

When This Page Helps

Photographers plan shoots around golden hour. Astronomers need to know when true darkness begins. Outdoor enthusiasts plan activities around usable daylight. This calculator gives precise twilight timing for any location and season.

How to Use the Inputs

1. Enter your latitude and longitude, or select a preset city.
2. Set your UTC time zone offset.
3. Enter the day of year (1 = Jan 1, 172 = Jun 21, 355 = Dec 21).
4. Review sunset time and all three twilight phase end times.
5. Check the golden hour window for photography planning.
6. Use the monthly table to see seasonal variation.

Example Calculation

Tips & Best Practices

• Golden hour starts about 1 hour before sunset and offers the warmest light.
• Blue hour is the 20-30 minutes after civil twilight — perfect for urban photography.
• At far northern latitudes in summer, astronomical twilight may never end (white nights).
• Sunset is typically 2-4 minutes later than geometric calculations predict, due to atmospheric refraction.

When To Use This Calculator

Calculate sunset time, twilight phases, golden hour, and monthly sunset table for any location. Includes civil, nautical, and astronomical twilight. Use it when you need a repeatable calculation in the physics / general category and want the setup, result, and supporting values kept together. This is especially helpful when small input changes, unit choices, or rounding decisions can change the final number.

How To Check The Result

Start by confirming that the inputs match the formula shown on the page. Then compare the main output with the worked example and any secondary values shown by the calculator. If the result will be used in another calculation, keep extra precision until the final step and record the assumptions beside the number.

Practical Notes

Treat the result as a calculation aid rather than a substitute for context. For schoolwork, include the formula and substitution steps. For planning, technical, financial, or health-related decisions, verify important numbers against primary records, current rules, or a qualified professional before acting on them.

Frequently Asked Questions

• Why are there different types of twilight?

  They correspond to how much scattered sunlight remains. Civil: enough for outdoor work. Nautical: horizon visible at sea. Astronomical: sky dark enough for most observations.

• What is the golden hour exactly?

  No precise definition — roughly the last 60 minutes before sunset (and first 60 after sunrise). The sun is low, warm-toned, and casts long soft shadows.

• Why do sunset colors happen?

  At low angles, sunlight passes through more atmosphere. Short wavelengths (blue) scatter away, leaving long wavelengths (red, orange). Dust and humidity intensify the colors.

• Do mountains affect sunset time?

  Yes — mountains to the west block the sun earlier. This calculator gives flat-horizon times; actual sunset may be 5-15 minutes earlier in mountainous terrain.

• What are white nights?

  At latitudes above ~60° in summer, the sun never goes more than 18° below the horizon, so it never gets truly dark. St. Petersburg (59.9°N) is famous for this.

• Why is sunset later in summer?

  Solar declination pushes the sun's path further north (in the Northern Hemisphere), creating a longer arc across the sky and later sunset times.