How to Calculate
San Fu Dates

San Fu dates are calculated using the Earthly Branches and Heavenly Stems system in the Daoist Calendar. You’re going to need a Chinese almanac, a list of the 24 solar terms for the year, and a western calendar to calculate the conversion.

San Fu dates are all yang metal days (庚 geng) that occur
after the summer solstice and are 10 days apart

• Note that all these calculations are based on timing in the northern hemisphere

• You start by finding the date for the summer solstice (2025 = June 20th)

• The initial fu begins on the third 庚 geng day after the summer solstice
  (2025 = (1) June 30, (2) July 10th, (3) July 20th)

• The middle fu begins ten days later on the fourth 庚 geng day after the summer solstice (2025 = July 30th)

• Look up the solar date for “Lì Qiū / 立秋 / Autumn Begins” (2025 = August 7th)

• The final fu is the first 庚 geng day after “Lì Qiū / 立秋 / Autumn Begins” (2023 = August 9th)

Every year is a little different, but there is often an extra 庚 geng day between the middle and last fu days that you’ll need to keep an eye out for. Some years we’ll get three San Fu days, and some years we’ll get four. In 2025, there are only 3 dates.