Why Birth Time Matters in Saju
The clock on the wall is not the sun. In Saju, the difference is a whole pillar.
Of the four pillars, one comes from the hour. Without a birth time you have three, which is still a real chart — but the missing pillar is the one traditionally associated with inner life and later-life direction, and removing it changes the element balance and the Ten God tally that the rest of the reading is built on.
Two-hour blocks
Saju divides the day into twelve two-hour branches, beginning with 子 from 11 PM to 1 AM. A birth ten minutes from the edge of a block is ten minutes from a different hour pillar, which is why a time remembered as "around three" is weaker evidence than it feels.
Longitude: the correction most services skip
Legal time is set by a whole zone; the sun is set by your longitude. Korean clocks are pegged to the 135°E meridian while Seoul sits near 127°E — about eight degrees west, or roughly 32 minutes. That alone turns a birth recorded at 11:30 PM in Seoul into 10:57 PM. There is a second correction most services skip entirely: the equation of time, the gap between the real sun and a uniform fictitious one, which reaches about +16 minutes in early November and −14 minutes in mid-February. Apply both and the same birth lands at 11:14 PM — back on the other side of the midnight boundary. The two corrections can point in opposite directions, so applying only one is not a smaller version of applying both.
Daylight saving and historical zones
The zone your birthplace uses today may not be the zone it used then. Korea ran on UTC+08:30 from 1954 to 1961 and observed daylight saving in 1987 and 1988. United States daylight-saving rules changed in 1974, 1975, 1987 and 2007. An hour of uncorrected daylight saving is half a Saju hour.
If you genuinely do not know
Ask a parent, or check a birth certificate — in many jurisdictions the time is recorded. Failing that, a three-pillar reading is honest and useful, and far better than a chart with an invented hour in it. What you should not accept is a service that quietly supplies an hour and does not tell you it did.
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