About

Manse Clock (gcdo.kr) is a free Manse calendar that calculates and displays, in real time, the Four Pillars of this very moment.

What this site does

To read a Four Pillars chart you first need the Stem-Branch pair of that moment. In the past you had to leaf through a thick Manse calendar book for the year, month and day pillars, and look the hour pillar up separately in a table.

This site reduces that to a single screen. As soon as you open it, the year, month, day and hour pillars for the current momentappear at once and refresh every second. Tapping a date on the calendar, or one of the twelve double-hour cells, recalculates the four pillars for that point in time.

This site does not interpret charts. Calculating the Stem-Branch pairs accurately and showing themis where its job ends.

Calculation standards

A Manse calendar's results change with the standards it adopts. Every standard this site uses is disclosed below.

PillarWhen it changes
Year Pillar (年柱)not January 1, but the moment Start of Spring (立春) begins
Month Pillar (月柱)not the 1st of each month, but the moment a Solar Term (節) begins (12 of the 24 terms)
Day Pillar (日柱)not midnight, but 23:30 (when the Ja Hour begins)
Hour Pillar (時柱)every 2 hours, with the boundary at XX:30 (Ja Hour: 23:30)

All times are shown in Korea Standard Time (KST).

Why 23:30 and not 23:00 — Korea Standard Time is based on 135°E, while Seoul sits at about 127.5°E. That 7.5-degree gap equals about 30 minutes, so Seoul's true solar time runs 30 minutes behind standard time. That is why the Ja Hour starts at 23:30. This site uses the orthodox standard, which does not set the Late Ja Hour (夜子時) apart.

Solar Term data

Solar Term entry times are calculated from the 24 Solar Terms data published by the Korea Astronomy and Space Science Institute. Not only the date but the hour and minute are used, so if Start of Spring falls at 05:02 on February 4, then 05:01 and 05:03 yield different year and month pillars.

The Solar Term data on the main screen and the Solar Term table in the basics guideboth come from the same source file. The two screens can never disagree.

Pricing

Free, with no sign-up. Running costs are covered by the ads on the page.

Operation

This site is run by one person. Inquiries are received through the contact page.

What this site provides is the result of a metaphysical calculation. It is not suitable as a basis for medical, legal or financial decisions. Details are set out in the Terms of Service.