How much of the reading is lost without the Hour pillar?

Two of the eight characters, so a quarter of the raw material, and the part traditionally linked to children, later life and the inner self. The Day Master, the element balance and most stars still come from the other six characters, so a three-pillar reading is real, just less detailed.

Is it better to guess an hour than to leave it blank?

No. A wrong hour adds two wrong characters and can flip the strength of the Day Master. If you know a rough window, use the animal-hour choice; if you know nothing, choose No. Both are honest, and the chart text tells the AI which one you used.

My birth certificate says 12:00 exactly. Is that real?

Often not. Round times on old records are frequently estimates. Treat 12:00, 6:00 and similar as a rough window (the Horse hour, 11 AM to 1 PM, for noon) rather than an exact minute.

No birth time? You can still read your Saju

What the Hour pillar adds

The Hour pillar is the fourth pair of characters, chosen by which of twelve two-hour windows the birth falls in. In traditional reading it stands for children, the later part of life and the private self, and its two characters count toward the element balance and the strength of the Day Master. Without it you still have the Year, Month and Day pillars, six characters, including the Day Master, the Month branch that sets the season, and the Day branch that describes partnership.

Where to look for the time

Birth certificate. In the United States most states record the time of birth on the long-form certificate. Many European and Asian countries do as well. Korea’s family register often does not, but the hospital record might.
Hospital records and baby books. Discharge papers, the hospital bracelet, a baby book or the first photo’s timestamp are common places it survives.
Parents and relatives. Ask for the story rather than the number. “It was just before dinner” or “the sun was coming up” is enough to pick an animal hour.

Rough time: the animal hours

If you know the window but not the minute, choose Roughly and pick one of the twelve animal hours. Each covers two hours: the Snake hour is 9 to 11 in the morning, the Horse hour 11 to 1, and so on. SajuPaste uses the middle of the window to compute the Hour pillar, which is the correct character for any time inside it. A birth “around 10” and a birth at 10:40 give the same Hour pillar.

The windows are in true solar time, which can differ from the clock by up to an hour depending on where you were born and whether daylight saving was in force. SajuPaste corrects for this from your birthplace, so pick the window by the clock time you were told and let the site adjust.

No time at all: the three-pillar chart

When you choose No, SajuPaste does the following so that the missing pillar does not distort the rest:

The Hour pillar is left blank in the chart and marked unknown in the copied text.
The five-element percentages are computed from the six known characters only.
The Day Master strength and the useful element exclude the hour.
Interactions involving the hour branch are omitted rather than guessed.
The text tells the AI to treat the Hour pillar as unavailable, so it does not invent one.

Two edge cases

Born between 11 PM and 1 AM. This is the Rat hour (子), which straddles midnight. Some schools move the day pillar to the next day from 11 PM; SajuPaste keeps the calendar day and notes this in the text so a reader can apply either convention.
Born during a daylight-saving change. Once a year a clock hour does not exist, and once a year it happens twice. SajuPaste resolves both cases automatically and flags them in the calculation notes.