True solar time calculator
BaZi and Purple Star Astrology read the time by the sun where you were born, not by the clock. Clocks follow a meridian that can be hundreds of kilometres away — and in Malaysia and Singapore, before 1982, the clocks themselves were set differently from today.
How far the sun runs behind the clock, city by city
Malaysia and Singapore both keep UTC+8 today, a clock set to the 120°E meridian. Both lie far west of it, so the sun is always behind the clock — in Kuala Lumpur by more than an hour. This is the true solar time at 12:00 noon by the clock today, 27 October 2026, in each city.
| City | All year, from longitude | Sun time at 12:00 today |
|---|---|---|
| Kuala Lumpur | -73 min | 11:03 |
| Singapore | -65 min | 11:11 |
| George Town | -79 min | 10:57 |
| Ipoh | -76 min | 11:00 |
| Malacca | -71 min | 11:05 |
| Johor Bahru | -65 min | 11:11 |
| Kota Bharu | -71 min | 11:05 |
| Kuantan | -67 min | 11:09 |
| Kuching | -39 min | 11:37 |
| Sibu | -33 min | 11:43 |
| Kota Kinabalu | -16 min | 12:00 |
| Hong Kong | -23 min | 11:53 |
| Taipei | +6 min | 12:22 |
The longitude part never changes: each degree is four minutes of sun time. Today’s sun time also carries the time of year — the equation of time, from the Earth’s tilted, elliptical orbit — which moves the sun by up to about 16 minutes either way over a year.
Malaysia and Singapore changed their clocks
True solar time starts from the timezone the clocks actually kept that year. Work out a birth before 1982 with today’s UTC+8 and it is half an hour out — enough to land in a different two-hour period. These are the changes as the IANA tz database records them, the same data this site’s charts use.
Peninsular Malaysia and Singapore
| 1900-12-31 → 1905-05-31 | UTC+6:55 |
| 1905-05-31 → 1932-12-31 | UTC+7 |
| 1932-12-31 → 1941-08-31 | UTC+7:20 |
| 1941-08-31 → 1942-02-15 | UTC+7:30 |
| 1942-02-15 → 1945-09-11 | UTC+9 |
| 1945-09-11 → 1981-12-31 | UTC+7:30 |
| 1981-12-31 → now | UTC+8 |
Sarawak and Sabah
| 1926-02-28 → 1932-12-31 | UTC+7:30 |
| 1932-12-31 → 1942-02-15 | UTC+8 |
| 1942-02-15 → 1945-09-11 | UTC+9 |
| 1945-09-11 → now | UTC+8 |
Also: from mid-September to mid-December each year, 1935–1941, the clocks ran on UTC+8:20, a seasonal summer time.
How much does it matter? For about one in four people born in Peninsular Malaysia or Singapore before 1982, it changes the main star of their Purple Star chart. How that was measured. Every clock change, region by region
What true solar time is
Clock time is agreed, not observed: a whole timezone shares the time of one meridian. True solar time is where the sun actually stood at the place you were born — the moment it is highest in the sky is noon, 12:00, there.
The gap has two parts: how far the birthplace is from the timezone’s meridian, at four minutes a degree, and the time of year, up to about 16 minutes. BaZi and Purple Star Astrology split the day into twelve two-hour periods, so half an hour can move a birth into a different one.
It can move the date, too: in Malaysia a birth just after midnight on the clock is often still after 11pm the evening before by the sun, the one hour in which schools disagree about the day pillar. Born between 11pm and midnight: which day is yours.