Day Light Calculator

Daylight duration is the total amount of time between sunrise and sunset on a given day at a specific location[citation:1][citation:8]. It is the period when the sun is above the horizon and natural light is available[citation:11][citation:12].

Key points:

• ✅ Daylight duration varies by latitude — locations closer to the equator have more consistent day lengths throughout the year
• ✅ It varies by season — longer days in summer, shorter in winter
• ✅ It is measured in hours and minutes (e.g., 14h 30m)
• ✅ The calculator accounts for atmospheric refraction, which makes the sun appear above the horizon slightly earlier and set slightly later than the geometric calculation[citation:5][citation:9][citation:12]

The Daylight Duration Calculator supports any location on Earth by using latitude and longitude coordinates[citation:1][citation:12]. You can either:

• ✅ Search for a city — Choose from a database of major global cities with pre-set coordinates
• ✅ Enter custom coordinates — For precise locations, enter latitude and longitude manually[citation:1][citation:8]

The calculator uses the selected city's time zone to display sunrise and sunset times in local time[citation:12].

The calculator is based on the NOAA Solar Calculator and Jean Meeus's Astronomical Algorithms, which are considered highly accurate for solar calculations[citation:5][citation:9][citation:11].

• ✅ Theoretical accuracy: Within ±1 minute for locations between +/-72° latitude[citation:5][citation:9]
• ✅ Outside +/-72° latitude: Within approximately 10 minutes
• ✅ Atmospheric effects: Actual observed times may vary slightly due to atmospheric conditions (temperature, pressure, humidity)[citation:5][citation:9]
• ✅ Refraction correction: The calculator applies a standard atmospheric refraction correction of 0.833° for sunrise and sunset[citation:5][citation:9][citation:12]

For critical applications (navigation, legal, safety), always verify against official local astronomical almanacs and current operational sources[citation:6].

Yes. The Daylight Duration Calculator works with any valid date:

• ✅ Current date: Calculates today's daylight duration
• ✅ Past dates: Find daylight duration for any historical date
• ✅ Future dates: Plan for future events (travel, photography, outdoor activities)
• ✅ Date range: Some versions allow comparing daylight across multiple dates

The calculator works for dates between 1800 and 2100 with high accuracy. Results outside this range may have higher margins of error[citation:5][citation:9].

Yes. The Daylight Duration Calculator uses the time zone information for each city, including any Daylight Saving Time (DST) adjustments. Sunrise and sunset times are displayed in local time, so DST is automatically applied when the selected date falls within the DST period for that location[citation:6][citation:12].

The calculator handles extreme latitudes where polar day (24-hour daylight) or polar night (24-hour darkness) occur[citation:5][citation:9][citation:11]. In these cases:

• ✅ Polar day: When the sun never sets, the daylight duration is displayed as 24h 00m
• ✅ Polar night: When the sun never rises, the daylight duration is displayed as 0h 00m
• ✅ Twilight variations: The calculator also shows twilight periods (civil, nautical, astronomical) which may be useful in polar regions[citation:11]

These events occur at latitudes above the Arctic Circle (66.5°N) and below the Antarctic Circle (66.5°S)[citation:5][citation:9].

The calculator provides a comprehensive breakdown of solar information:

• ✅ Sunrise time – When the sun appears above the horizon[citation:1][citation:8][citation:12]
• ✅ Sunset time – When the sun disappears below the horizon[citation:1][citation:8][citation:12]
• ✅ Daylight duration – Total hours and minutes of sunlight[citation:1][citation:8]
• ✅ Solar noon – The time when the sun reaches its highest point in the sky[citation:12]
• ✅ Twilight times – Civil, nautical, and astronomical dawn and dusk[citation:5][citation:9][citation:11]
• ✅ Night duration – Total darkness between sunset and sunrise

Yes! The Daylight Duration Calculator is an excellent tool for travel planning and outdoor activities[citation:6]. It can help you:

• ✅ Plan photography trips – Know when to expect golden hour or blue hour light
• ✅ Schedule outdoor activities – Maximize daylight for hiking, sightseeing, or events
• ✅ Compare destinations – See which cities have longer daylight hours during your travel dates
• ✅ Understand local conditions – Learn about seasonal changes in daylight at your destination

Twilight is the period when the sun is below the horizon but still illuminates the sky. There are three types[citation:11][citation:12]:

• ✅ Civil twilight (−6°): The brightest twilight; objects are clearly visible, and outdoor activities can continue[citation:11][citation:12]
• ✅ Nautical twilight (−12°): The horizon is still visible, useful for navigation[citation:11][citation:12]
• ✅ Astronomical twilight (−18°): The sky is dark enough for most astronomical observations[citation:11][citation:12]

Twilight times are useful for photographers (golden hour), astronomers, sailors, and anyone planning outdoor activities.

Daylight duration varies due to the Earth's axial tilt of approximately 23.5°[citation:5][citation:9]:

• ✅ Summer solstice (June): Longest day of the year in the Northern Hemisphere
• ✅ Winter solstice (December): Shortest day of the year in the Northern Hemisphere
• ✅ Equinoxes (March, September): Nearly equal day and night worldwide

The variation is more extreme at higher latitudes and less noticeable near the equator. For example, Oslo, Norway can have over 18 hours of daylight in summer, while Singapore has roughly 12 hours year-round[citation:10].

Yes. The Daylight Duration Calculator on Royal Calc is completely free to use. All calculations are performed directly in your browser using astronomical algorithms[citation:1][citation:8]. No registration or payment is required, and your data remains private and secure.