What is Can Chi? Heavenly Stems, Earthly Branches and the cycle

Can Chi is an ancient time-keeping system that pairs Heavenly Stems and Earthly Branches to name years, months, days and hours. It underpins the lunar calendar, Tử Vi, day selection and age compatibility.

The 10 Heavenly Stems

Giáp, Ất, Bính, Đinh, Mậu, Kỷ, Canh, Tân, Nhâm, Quý — each with an element and yin/yang: Giáp/Ất (Wood), Bính/Đinh (Fire), Mậu/Kỷ (Earth), Canh/Tân (Metal), Nhâm/Quý (Water).

The 12 Earthly Branches

Tý, Sửu, Dần, Mão, Thìn, Tỵ, Ngọ, Mùi, Thân, Dậu, Tuất, Hợi — the 12 zodiac animals (Rat, Ox, Tiger, Cat, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig).

The 60-year cycle

Pairing stems and branches in turn gives 60 combinations (Giáp Tý, Ất Sửu, Bính Dần…), completing a full round every 60 years.

Reading a year's Can Chi

• Stem: from the last digit of the solar year (…4 Giáp, 5 Ất, 6 Bính, 7 Đinh…).
• Branch: from the year modulo 12. For example, 2026 → Horse.

So 2026 is Bính Ngọ. No hand-calculation needed — see it on the perpetual calendar, with day and hour stems too.

In practice

Can Chi drives compatibility (trine/clash by branch, stem harmony) — see age compatibility — and day selection by day pillar at Choose a day. The nạp âm destiny element also derives from the birth-year pillar — see feng shui by element.

Can Chi is the ancient calendrical foundation of many arts — understanding it makes the lunar calendar and Tử Vi far easier to read.