True solar time · By city
True Solar Time in Singapore
Auspice ·
新加坡 · 真太阳时
In Singapore, true solar time runs 18 to 79 minutes behind the clock. Across every clock minute of 1980, 1990, 2000, 2010, 48.1% land in a different BaZi hour pillar once corrected, and 4.0% on a different day pillar.
How often does the hour pillar change in Singapore?
| Clock minutes whose hour pillar changes | 48.1% |
| Range across 1980, 1990, 2000, 2010 | 29.4% – 54.4% |
| During daylight saving | no daylight saving |
| Outside daylight saving | 48.1% |
| Share of minutes under daylight saving | 0.0% |
| Clock minutes whose day pillar changes | 4.0% |
| Correction range | −79 … −18 min |
From the 40-city study on the main true-solar-time page: every clock minute of 1980, 1990, 2000, 2010 in the Asia/Singapore time zone at 103.82°E, converted to true solar time. Minutes are weighted equally, so this is a per-minute figure, not a per-birth one. Data: /data/solar-time-study.json (CC BY 4.0).
Why the clock and the sun disagree here
Singapore is at 103.82°E; its standard clock follows the 120°E meridian (UTC+8). The earth turns one degree every four minutes, so the longitude part of the correction is −65 minutes, the same every day of the year. The equation of time adds a seasonal swing of roughly −15 to +16 minutes. No daylight saving applied in any of the study years, so outside the equation of time the correction does not move through the year.
Singapore's clock since 1940
A chart has to use the clock that was in force on the birth date, not today’s. The table below is read directly from the IANA time-zone database the calculator uses, so it lists exactly the offsets a chart for each period is computed with.
| From | Until | Clock | Longitude part | Note |
|---|---|---|---|---|
| already in use in 1940 | 1 September 1941 | UTC+7:20 | −25 min | — |
| 1 September 1941 | 16 February 1942 | UTC+7:30 | −35 min | — |
| 16 February 1942 | 11 September 1945 | UTC+9 | −125 min | — |
| 11 September 1945 | 1 January 1982 | UTC+7:30 | −35 min | — |
| 1 January 1982 | today | UTC+8 | −65 min | — |
Dates are the local day the clock changed. The longitude part is what the correction would be from longitude alone on that clock.
Worked examples for Singapore
Each birth is cast twice by the same engine as the calculator: once on the clock time as written, once corrected to true solar time. Same-day convention for the late Rat hour.
15 June 1975, 13:50
A 1:50 pm birth in 1975, when Singapore clocks still ran on UTC+7:30.
| By the clock | By the sun | |
|---|---|---|
| Time | 13:50 | 13:15 |
| Hour pillar | 丁未 (Goat hour) | 丁未 (Goat hour) |
| Day pillar | 壬辰 | 壬辰 |
Correction −35 min: daylight saving 0, longitude −35, equation of time 0. The hour pillar stays 丁未 (Goat hour).
15 June 1995, 13:50
The same date and clock time twenty years later, on UTC+8.
| By the clock | By the sun | |
|---|---|---|
| Time | 13:50 | 12:45 |
| Hour pillar | 丁未 (Goat hour) | 丙午 (Horse hour) |
| Day pillar | 丁丑 | 丁丑 |
Correction −65 min: daylight saving 0, longitude −65, equation of time 0. The hour pillar changes from 丁未 (Goat hour) to 丙午 (Horse hour).
11 February 1990, 23:30
A late-evening birth in February, when the equation of time pulls the sun a further quarter-hour behind.
| By the clock | By the sun | |
|---|---|---|
| Time | 23:30 | 22:10 |
| Hour pillar | 壬子 (Rat hour) | 辛亥 (Pig hour) |
| Day pillar | 丁未 | 丁未 |
Correction −79 min: daylight saving 0, longitude −65, equation of time −14. The hour pillar changes from 壬子 (Rat hour) to 辛亥 (Pig hour).
About the clock in Singapore
Singapore sits at about 103.8°E, while its clock is set to the 120.0°E meridian. On today's UTC+8 the sun is highest at roughly 13:05 by the clock, not at noon, before the seasonal swing of the equation of time is added.
The clock has not always been this far off. Singapore kept UTC+7:30 until the last day of 1981 and moved to UTC+8 at midnight on 1 January 1982, the same night Peninsular Malaysia did, so that the two kept one clock with Sabah and Sarawak. During the Japanese occupation, 1942 to 1945, clocks ran on Tokyo time, UTC+9. A birth certificate from 1981 and one from 1982 can show the same time of day and still refer to moments thirty minutes apart by the sun. That is also why the lowest of the four study years is 1980: it is the only one before the change.
There has been no seasonal daylight saving since the war, so the only moving part through the year is the equation of time.
To apply all of this to one birth, enter the date, clock time and Singapore as the birthplace in the free BaZi calculator. It uses the same historical clock and the same three-part correction, shows the arithmetic, and needs no account. For why the correction exists at all, see true solar time in BaZi; to check whether another calculator applies it, try the three test birth times.
Other cities: true solar time in Kuala Lumpur, true solar time in Vancouver, true solar time in Toronto, true solar time in New York.