Peninsular Malaysia: time zone history, and your birth hour
The clocks in Peninsular Malaysia have changed 8 times since 1900. Today they run on UTC+8; the last change was on 1 Jan 1982. A calculator that uses today’s offset for every birth is out by some minutes for anyone born in any of the different eras below.
Since 1925, the widest gap is the standard time from 1905: 60 minutes, enough to move about 50% of births into a different two-hour period.
Every era
| From – to | Clock | Versus today · births in another hour |
|---|---|---|
| 1 Jan 1900 – 1 Jan 1901 | UTC+6:47 local mean time | −73 min about 61% |
| 1 Jan 1901 – 1 Jun 1905 | UTC+6:55 local mean time | −65 min about 54% |
| 1 Jun 1905 – 1 Jan 1933 | UTC+7 standard time | −60 min about 50% |
| 1 Jan 1933 – 1 Jan 1936 | UTC+7:20 summer time | −40 min about 33% |
| 1 Jan 1936 – 1 Sep 1941 | UTC+7:20 standard time | −40 min about 33% |
| 1 Sep 1941 – 16 Feb 1942 | UTC+7:30 standard time | −30 min about 25% |
| 16 Feb 1942 – 11 Sep 1945 | UTC+9 wartime, on Tokyo time | +60 min about 50% |
| 11 Sep 1945 – 1 Jan 1982 | UTC+7:30 standard time | −30 min about 25% |
| 1 Jan 1982 – today | UTC+8 standard time | same |
The second figure in each row is the births moved into another two-hour period: about m/120 of them when the clock is m minutes out. For Kuala Lumpur, 30 minutes out from 1946 to 1981, the measured share is 26.0% of 4,000 sampled births.