Shabbat Timing and Candle Lighting Calculator
Calculate Shabbat candle lighting and havdalah times for your location
Understanding Shabbat Timing and Jewish Day Calculation
The Problem
Shabbat observance requires precise knowledge of sunset and twilight times, which vary dramatically based on geographic location and season. A person observing Shabbat in New York faces completely different timing than someone in Jerusalem or Reykjavik. Jewish tradition dictates that candle lighting occurs before sunset and havdalah (conclusion of Shabbat) occurs after nightfall, but the exact times depend on geographic latitude, longitude, timezone, and local religious custom. Calculating these times requires understanding solar elevation angles and the date-dependent position of the sun in the sky.
How Shabbat Timing Works
Jewish tradition divides each day from nightfall to nightfall (not midnight to midnight as in secular time). Shabbat begins with candle lighting (conventionally 18-20 minutes before sunset) and ends with havdalah (conventionally 42 minutes after sunset, based on when 3 stars become visible). These times vary by:
- Geographic Latitude: The farther from the equator, the more extreme seasonal variations. Arctic regions may have midnight sun or polar night.
- Date of Year: Summer has later sunsets; winter has earlier sunsets.
- Local Custom: Different communities use different offsets (18-25 minutes for candle lighting, 20-72 minutes for havdalah).
- Elevation: Higher elevations see sunset slightly later; this calculator uses sea-level approximation.
The Mathematics
Solar noon occurs when the sun reaches its highest point:
Where L is longitude (degrees) and E is the equation of time (minutes)
Hour angle at sunset (when solar elevation = 0 degrees):
Where φ is latitude and δ is solar declination
Worked Example
For Friday, December 20, 2024 in New York (latitude 40.7128°N, longitude -74.0060°W, UTC-5):
- Solar declination on winter solstice ≈ -23.44°
- Sunset time (solar elevation 0°) ≈ 4:28 PM
- Candle lighting (18 minutes earlier) ≈ 4:10 PM
- Havdalah (42 minutes after sunset) ≈ 5:10 PM
- Shabbat duration ≈ 60 minutes (very short in winter)
- Day length on this date ≈ 9 hours 23 minutes
Seasonal Variations
| Season / Latitude | Sunset Time (Example: NYC) | Candle Lighting | Havdalah | Day Length |
|---|---|---|---|---|
| Winter Solstice (Dec 21) | 4:28 PM | 4:10 PM | 5:10 PM | 9h 23m |
| Spring Equinox (Mar 20) | 6:36 PM | 6:18 PM | 7:18 PM | 12h 11m |
| Summer Solstice (Jun 21) | 8:30 PM | 8:12 PM | 9:12 PM | 15h 3m |
| Fall Equinox (Sep 23) | 6:39 PM | 6:21 PM | 7:21 PM | 12h 8m |
Limitations and Assumptions
- Simplified Solar Model: This calculator uses a simplified solar position algorithm. Precision to within 1-2 minutes is typical; exact times may vary by location-specific altitude and atmospheric conditions.
- Sea-Level Approximation: Elevation above sea level affects sunset time (higher elevations see sunset later). This calculator does not account for elevation.
- Atmospheric Refraction: The sun appears slightly higher in the sky due to atmospheric bending. Sunset may appear 2-3 minutes later than theoretical calculation.
- Custom Variation: Jewish communities use different offset values. Ashkenazi, Sephardi, Yemenite, and other traditions have different conventions.
- Three-Stars Definition: Havdalah timing based on "three stars of magnitude 3.5" requires clear skies and subjective observation. The 42-minute default is an approximation.
- Daylight Saving Time: This calculator does not account for daylight saving time changes. Adjust UTC offset accordingly.
- Arctic Regions: Above the Arctic Circle during summer, the sun never sets. This calculator may produce invalid results in polar regions.
- Leap Year: Calculations account for leap years; date must be valid for the given year.