If you have ever looked at a Japanese wall calendar or wedding venue brochure, you have likely noticed six two-character annotations printed beside each date: 先勝 (Sensho), 友引 (Tomobiki), 先負 (Senbu), 仏滅 (Butsumetsu), 大安 (Taian), and 赤口 (Shakko). Collectively called Rokuyo (六曜) or Rokki (六輝), these labels remain widely consulted in Japan when scheduling weddings, marriage registrations, house moves, car deliveries, and funerals.
Drawing on primary documentation from the National Diet Library (NDL) and the National Astronomical Observatory of Japan (NAOJ), this guide explains all six Rokuyo labels, their time-of-day interpretations, the (Lunar Month + Day) mod 6 rule, why the cycle jumps at lunar month boundaries, and concrete 2026–2027 date conversions.
- Depends on Both Lunar Month and Day: Convert the Gregorian date to the traditional lunisolar calendar (kyureki) and compute
(Lunar Month + Lunar Day) ÷ 6. The remainder maps to2: Sensho, 3: Tomobiki, 4: Senbu, 5: Butsumetsu, 0: Taian, 1: Shakko. - Resets on Lunar Day 1: Because the first day of every lunar month has a fixed starting label, the 6-day sequence jumps at month boundaries.
- Cultural Custom, Not a Binding Rule: Rokuyo reflects folk tradition rather than science or law. Prioritize participant availability and venue operating hours first.
Select any Gregorian date in your browser to view its Rokuyo label, traditional interpretation, lunisolar month and day, year/day干支 (Ganzhi), and 24 solar terms.
1. The Six Rokuyo Labels: Readings, Time Windows & Event Customs
Adapted from Chinese time-keeping divination and popularized on Japanese civilian calendars from the late Edo and Meiji periods onward, Rokuyo assigns one of six labels to each day. As the National Diet Library notes, interpretations vary by region and era, but the table below summarizes standard modern usage:
| Rokuyo Label | Reading | (Lunar Month + Day) mod 6 |
Favorable / Unfavorable Hours | Traditional Meaning & Etymology | Common Modern Scheduling Customs in Japan |
|---|---|---|---|---|---|
| 先勝 | Sensho (Sakigachi) |
Remainder 2 | Morning (~until 14:00) lucky Afternoon unlucky |
“Win by acting first.” Favors prompt action and morning starts | Popular for morning weddings, contract signings, and morning house moves |
| 友引 | Tomobiki | Remainder 3 | Morning & evening lucky Noon (11:00–13:00) unlucky |
Originally “a draw where neither side wins”; later folk-etymologized as “pulling friends along” | Second most popular day for weddings and celebrations after Taian. Avoided for funerals, and many Japanese crematoria close on Tomobiki |
| 先負 | Senbu (Sakimake) |
Remainder 4 | Afternoon lucky Morning unlucky |
“Lose by rushing ahead.” Favors calm matters and afternoon starts | Chosen for afternoon wedding receptions, meetings, and afternoon deliveries |
| 仏滅 | Butsumetsu | Remainder 5 | All day unlucky (some view afternoon as a fresh start) |
Originally “things end and renew” (物滅); later written as “even Buddha perishes” | Often avoided for traditional celebrations, though many modern couples choose “Butsumetsu discount” wedding packages. Funerals and memorial services are unaffected |
| 大安 | Taian | Remainder 0 (Divisible by 6) |
All day lucky | “Great peace / safety.” Considered auspicious all day for all undertakings | Highest demand for weddings, marriage registration (kon’in-todoke), house moves, ground-breaking ceremonies, and car deliveries |
| 赤口 | Shakko (Shakku) |
Remainder 1 | Only noon (11:00–13:00) lucky Morning & evening unlucky |
Associated with the ominous “Red Tongue” deity; traditionally cautions against fire and blades | Celebrations are often avoided except around the midday window (11:00–13:00) |
Even for people who do not follow fortune-telling, Rokuyo has two practical effects on logistics in Japan: (1) Wedding venues and moving companies book up fastest—and often charge peak rates—on weekend Taian and Tomobiki dates, and (2) many municipal crematoria schedule regular closures on Tomobiki, which directly affects funeral scheduling. To count exact days between ceremony milestones, see our Date Calculation Guide.
2. How Rokuyo Is Calculated: The (Lunar Month + Day) mod 6 Rule
You cannot calculate Rokuyo by plugging a Gregorian month and day into the formula. As explained in NAOJ’s guide to the traditional lunisolar calendar (kyureki), you must first convert the Gregorian date into its lunisolar month and day.
Determine which lunar month and day correspond to the target date (our Rokuyo & Lunar Calendar performs this conversion automatically). For example, November 9, 2026 corresponds to Lunar Month 10, Day 1 (十月初一). For Japanese imperial era conversions (Reiwa, Heisei, Showa), see the Japanese Era Conversion Guide.
Formula: (Lunar Month + Lunar Day) ÷ 6
For November 9, 2026 (Lunar Month 10, Day 1): (10 + 1) ÷ 6 = 11 ÷ 6 = 1 with remainder 5.
Note If a date falls in an intercalary leap month (uruzuki, e.g., Leap Month 4), use the same month number as the preceding regular month (4).
0 = Taian, 1 = Shakko, 2 = Sensho, 3 = Tomobiki, 4 = Senbu, 5 = Butsumetsu.
Remainder 5 gives Butsumetsu. Within the same lunar month, each subsequent day increases the remainder by 1, advancing through Sensho (2) → Tomobiki (3) → Senbu (4) → Butsumetsu (5) → Taian (0) → Shakko (1).
Why the Sequence Jumps at Lunar Month Boundaries
Each lunar month begins on the day of the astronomical new moon (Day 1 / tsuitachi) and lasts either 29 days (hollow month) or 30 days (full month). Because Day 1 of each lunar month starts on a fixed label, the 6-day cycle resets whenever a new lunar month begins:
| Lunar Month | Label on Lunar Day 1 | Days Sharing the Day-1 Label | Label on Day 29 | Label on Day 30 (if 30-day month) | Transition to Next Lunar Month Day 1 |
|---|---|---|---|---|---|
| Months 1 & 7 | Sensho (rem 2) | Days 1, 7, 13, 19, 25 | Day 29 = Shakko | Day 30 = Sensho | Next month (2 or 8) Day 1 is fixed to Tomobiki (skips Sensho after a 29-day month) |
| Months 2 & 8 | Tomobiki (rem 3) | Days 1, 7, 13, 19, 25 | Day 29 = Sensho | Day 30 = Tomobiki | Next month (3 or 9) Day 1 is fixed to Senbu (skips Tomobiki after a 29-day month) |
| Months 3 & 9 | Senbu (rem 4) | Days 1, 7, 13, 19, 25 | Day 29 = Tomobiki | Day 30 = Senbu | Next month (4 or 10) Day 1 is fixed to Butsumetsu (skips Senbu after a 29-day month) |
| Months 4 & 10 | Butsumetsu (rem 5) | Days 1, 7, 13, 19, 25 | Day 29 = Senbu | Day 30 = Butsumetsu | Next month (5 or 11) Day 1 is fixed to Taian (skips Butsumetsu after a 29-day month) |
| Months 5 & 11 | Taian (rem 0) | Days 1, 7, 13, 19, 25 | Day 29 = Butsumetsu | Day 30 = Taian | Next month (6 or 12) Day 1 is fixed to Shakko (skips Taian after a 29-day month) |
| Months 6 & 12 | Shakko (rem 1) | Days 1, 7, 13, 19, 25 | Day 29 = Taian | Day 30 = Shakko | Next month (1 or 7) Day 1 is fixed to Sensho (skips Shakko after a 29-day month) |
3. Worked Examples for 2026–2027 (Gregorian, Lunar, Rokuyo & Ganzhi)
You can verify each of the following 2026–2027 dates directly in our Rokuyo & Lunar Calendar (for more on the 60-year sexagenary cycle shown alongside Rokuyo, see the Japanese Zodiac / Eto Guide):
| Gregorian Date | Lunar Date (Tool Display) | (Lunar Month + Day) ÷ 6 |
Rokuyo Result | Year / Day Ganzhi | What This Example Demonstrates |
|---|---|---|---|---|---|
| Nov 8, 2026 (Sun) | Lunar Month 9, Day 30 (九月三十) |
$(9 + 30) \div 6 = 39 \div 6 = 6 \text{ rem } \mathbf{3}$ | Tomobiki (友引) | 丙午 / 丙戌 | Last day (Day 30) of Lunar Month 9; remainder 3 gives Tomobiki |
| Nov 9, 2026 (Mon) | Lunar Month 10, Day 1 (十月初一) |
$(10 + 1) \div 6 = 11 \div 6 = 1 \text{ rem } \mathbf{5}$ | Butsumetsu (仏滅) | 丙午 / 丁亥 | Lunar Month 10 Day 1 Reset: Jumps from Tomobiki (rem 3) directly to Butsumetsu (rem 5), skipping Senbu (rem 4) |
| Nov 10, 2026 (Tue) | Lunar Month 10, Day 2 (十月初二) |
$(10 + 2) \div 6 = 12 \div 6 = 2 \text{ rem } \mathbf{0}$ | Taian (大安) | 丙午 / 戊子 | Lunar 10/2: $10 + 2 = 12$ is divisible by 6 (remainder 0 = Taian) |
| Dec 8, 2026 (Tue) | Lunar Month 10, Day 30 (十月三十) |
$(10 + 30) \div 6 = 40 \div 6 = 6 \text{ rem } \mathbf{4}$ | Senbu (先負) | 丙午 / 丙辰 | Last day (Day 30) of Lunar Month 10; remainder 4 gives Senbu |
| Dec 9, 2026 (Wed) | Lunar Month 11, Day 1 (冬月初一) |
$(11 + 1) \div 6 = 12 \div 6 = 2 \text{ rem } \mathbf{0}$ | Taian (大安) | 丙午 / 丁巳 | Lunar Month 11 Day 1 Reset: Jumps from Senbu (rem 4) directly to Taian (rem 0), skipping Butsumetsu (rem 5) |
| Jan 1, 2027 (Fri) | Lunar Month 11, Day 24 (冬月廿四) |
$(11 + 24) \div 6 = 35 \div 6 = 5 \text{ rem } \mathbf{5}$ | Butsumetsu (仏滅) | 丙午 / 庚辰 | Gregorian New Year’s Day 2027 is Lunar 11/24, yielding Butsumetsu |
| Feb 6, 2027 (Sat) | Lunar Month 1, Day 1 (正月初一) |
$(1 + 1) \div 6 = 2 \div 6 = 0 \text{ rem } \mathbf{2}$ | Sensho (先勝) | 丁未 / 丙辰 | 2027 Lunar New Year: Lunar Month 1 Day 1 always starts on Sensho, and the lunar year stem-branch advances to 丁未 |
4. How to Verify Any Date in the Rokuyo & Lunar Calendar Tool
To check any date between 1900 and 2100 in the Rokuyo & Lunar Calendar:
- Pick a Gregorian Date: Enter a date in the date picker (
1900-01-01to2100-12-31) or click Today. - Read the Rokuyo Label & Guidance: Check the primary badge (e.g.,
大安 (Taian)or仏滅 (Butsumetsu)) and its traditional time-of-day description. - Inspect Lunar & Sexagenary Details:
- Lunar Date: Displayed in traditional notation (e.g.,
十月初一for Month 10, Day 1;冬月= Month 11,臘月= Month 12,正月= Month 1). - Year & Day Ganzhi: Shows the 60-cycle stem-branch pair for the lunar year and day.
- Solar Term (24 Sekki): Appears when the selected date coincides with one of the 24 solar terms.
- Lunar Date: Displayed in traditional notation (e.g.,
Look up Rokuyo and lunar dates in the Rokuyo Calendar, or convert Japanese imperial eras (Reiwa, Heisei, Showa) in the Wareki Converter.
5. Related Tools & Further Reading
- Rokuyo & Lunar Calendar: Look up Rokuyo, lunisolar dates, year/day Ganzhi, and 24 solar terms for any date from 1900 to 2100.
- Japanese Zodiac (Eto / Sexagenary Cycle) Guide: Learn how the 10 Heavenly Stems and 12 Earthly Branches combine into a 60-year cycle (with the Eto Calculator).
- Japanese Era (Wareki) Conversion Guide: Convert between Gregorian years and Meiji, Taisho, Showa, Heisei, and Reiwa eras (with the Wareki Converter).
- Date & Duration Calculation Guide: Count days between dates and understand inclusive vs. exclusive boundary rules (with the Date Calculator).
- Age Calculation Guide: Compare chronological age and traditional East Asian age counting (with the Age Calculator).
- Utility Tools Category: Browse all calendar, date, and everyday calculation tools.
Verification & Update Log
On November 9, 2026, we verified the lunar assignment rules and historical descriptions against the National Diet Library Rokuyo reference and NAOJ’s lunisolar calendar FAQ, adding the complete 6-label custom table, the month-end boundary transition table, and verified 2026–2027 worked examples.
FAQ
What is the order of the six Rokuyo labels and how are they calculated from the lunar calendar?
Within any single lunar month, Rokuyo cycles in the 6-day order Sensho → Tomobiki → Senbu → Butsumetsu → Taian → Shakko. Mathematically, add the lunar month number and lunar day number and divide by 6: remainder 2 = Sensho, 3 = Tomobiki, 4 = Senbu, 5 = Butsumetsu, 0 (divisible by 6) = Taian, and 1 = Shakko. For example, November 9, 2026 is Lunar Month 10, Day 1, so (10 + 1) ÷ 6 leaves remainder 5 (Butsumetsu).
Why does the 6-day Rokuyo sequence sometimes skip a label on the calendar?
The first day (new moon) of each lunar month is assigned a fixed starting label: months 1 & 7 start on Sensho, 2 & 8 on Tomobiki, 3 & 9 on Senbu, 4 & 10 on Butsumetsu, 5 & 11 on Taian, and 6 & 12 on Shakko. When one lunar month ends and the next begins on Day 1, the sequence resets. For instance, November 8, 2026 (Lunar 9/30) is Tomobiki, and November 9, 2026 (Lunar 10/1) resets directly to Butsumetsu, skipping Senbu.
Are funerals legally or religiously forbidden on Tomobiki in Japan?
No. Avoiding funerals on Tomobiki is neither a law nor a core Buddhist doctrine. Because the characters for Tomobiki literally mean 'pulling friends along,' a folk custom arose against holding funerals on that day. In practice, however, many municipal and private crematoria in Japan schedule their regular maintenance closures on Tomobiki, while wakes (tsuya) are still commonly held.
Does the same Gregorian date (such as January 1) have the same Rokuyo every year?
No. Because Rokuyo is calculated from the lunisolar calendar (kyureki), which shifts by roughly 11 days per year relative to the Gregorian calendar and periodically inserts leap months (uruzuki), a fixed Gregorian date corresponds to a different lunar date—and usually a different Rokuyo—each year (e.g., January 1, 2026 is Senbu, whereas January 1, 2027 is Butsumetsu).
