三枚銅錢起卦怎麼做？擲六次的規則與記錄方式
作者：Wei Chun Chuang・2026-10-24
讀《易經》之前，要先有一個卦。最常見的取卦方式是三枚銅錢擲六次。這篇把規則、換算與記錄方式一次寫清楚，照著做就能得到一個完整的六爻卦。
為什麼是三枚錢？
一爻只有陰、陽兩種，但《易經》的讀法還要分「會不會變」，所以一次需要四種結果。三枚錢各有兩面，正背的數量組合剛好產生四種總和，正好對應四種爻。這是三枚錢被沿用下來的原因。
正面背面怎麼換算成 2 和 3？
常見做法是：有字的那一面算 2，另一面算 3。這只是約定，重點是每次都用同一套，而且擲之前就講清楚。三枚一起擲，把三個數字加起來，可能的總和只有四個：
- 6＝2＋2＋2，老陰，陰爻且是變爻
- 7＝2＋2＋3，少陽，陽爻不變
- 8＝2＋3＋3，少陰，陰爻不變
- 9＝3＋3＋3，老陽，陽爻且是變爻
記法很簡單：六和九會變，七和八不變；六、八是陰，七、九是陽。
為什麼要擲六次，而且從下往上？
一個卦有六爻，所以要擲六次，每次決定一爻。順序固定從最下面那一爻（初爻）開始，第二次是第二爻，一路往上到第六次的上爻。這個方向不能倒過來寫，不然整個卦會變成另一個卦。
怎麼把六爻記下來？
最穩的方式是先記數字，再畫線：
- 準備一張紙，從下往上留六格。
- 每擲一次，把總和（6、7、8、9）寫進對應那一格。
- 六次擲完後，把 7、9 畫成一條實線（陽爻），6、8 畫成中間斷開的線（陰爻）。
- 在 6 和 9 的旁邊做個記號，那些就是變爻。
保留原始數字很重要：只畫線的話，會分不出那條陰爻是 6 還是 8，變爻的資訊就不見了。
哪些是變爻？擲完之後要讀什麼？
六爻畫完得到的卦叫「本卦」，先讀它的卦名、卦辭與象。接著看有沒有變爻：把每個 6 改成陽爻、每個 9 改成陰爻，不是變爻的照舊，得到的第二個卦叫「之卦」。傳統讀法是本卦談現在的狀況，變爻的爻辭談正在鬆動的地方，之卦談可能走向的局面。沒有變爻時就只讀本卦。
蓍草法是什麼？
銅錢法之前，更早的做法是用五十根蓍草反覆分揀取爻。兩種方法都會得到 6、7、8、9，但出現的機率不一樣：銅錢法四種結果的機率是 1、3、3、1，蓍草法則讓少陰出現得比少陽多，老陰比老陽少。兩套系統都有人沿用，選定一種、固定使用就好。
一句老實話
起卦是一套把問題寫清楚、再從一個固定參照點重新思考的練習。起卦前怎麼把問題問對，見易經要怎麼問問題。它不會預知結果，也不保證任何事情發生。醫療、法律、投資這類重大決定，請找合格的專業人士。
常見問題
- 一定要用古代的銅錢嗎？
- 不一定。規則只需要三枚兩面可區分的錢幣，而且要先講清楚哪一面算 2、哪一面算 3。古銅錢是傳統習慣，不是必要條件。
- 沒有變爻怎麼辦？
- 六爻全是七或八時就沒有變爻，也沒有之卦，只讀本卦的卦辭與象。這是正常結果，不需要重擲。
- 同一個問題可以重擲嗎？
- 傳統做法是一事一卦，不滿意就重擲會失去參照點。想換角度時，建議改寫成另一個更具體的問題再擲。
想用 App 練習？
想不用銅錢也能照規則練習，易見網頁版免登入、免費，可以直接擲卦並查完整六十四卦。另外，易見是一款教你讀《易經》的 iPhone 課程 App，目前已送 App Store 審核，尚未上架。
How do you cast an I Ching hexagram with three coins?
作者：Wei Chun Chuang・2026-10-24
Before you can read the I Ching you need a hexagram. The most common way to get one is to throw three coins six times. This article sets out the rules, the arithmetic and the way to write the result down, so you end up with one complete six-line hexagram.
為什麼是三枚錢？
A line is either yin or yang, but I Ching readings also distinguish whether a line is changing, so each throw needs four possible outcomes. Three coins with two faces each produce exactly four different totals, one for each kind of line. That is why three coins became the standard.
How do heads and tails map to 2 and 3?
The usual convention is that the inscribed face counts as 2 and the other face as 3. The labels are arbitrary; what matters is using the same rule every time and deciding before you throw. Throw all three together and add the numbers. Only four totals are possible:
- 6 = 2+2+2, old yin: a yin line that is also a changing line
- 7 = 2+2+3, young yang: a yang line that does not change
- 8 = 2+3+3, young yin: a yin line that does not change
- 9 = 3+3+3, old yang: a yang line that is also a changing line
An easy way to remember: 6 and 9 change, 7 and 8 do not; 6 and 8 are yin, 7 and 9 are yang.
Why six throws, and why from the bottom up?
A hexagram has six lines, so you throw six times, each throw fixing one line. The order is always from the bottom line upward: the first throw is the bottom line, the second is the second line, and the sixth throw is the top line. Writing them in the other direction gives you a different hexagram.
How do you write the six lines down?
The safest method is to record the numbers first and draw the lines afterwards:
- Leave six slots on a sheet of paper, counting upward from the bottom.
- After each throw, write the total (6, 7, 8 or 9) in the matching slot.
- When all six are down, draw 7 and 9 as a solid line (yang) and 6 and 8 as a line broken in the middle (yin).
- Mark every 6 and every 9: those are the changing lines.
Keeping the original numbers matters. If you only draw lines, you cannot tell whether a yin line came from a 6 or an 8, and the changing-line information is lost.
Which lines are changing, and what do you read next?
The hexagram you have drawn is the primary hexagram. Read its name, its text and its image first. Then check for changing lines: turn every 6 into a yang line and every 9 into a yin line, leave the others as they are, and the second hexagram you get is the resulting hexagram. The traditional reading treats the primary hexagram as the present situation, the texts of the changing lines as what is in motion, and the resulting hexagram as where the situation may be heading. With no changing lines you read the primary hexagram alone.
What about the yarrow-stalk method?
Before coins, the older method sorted fifty yarrow stalks repeatedly to produce each line. Both methods yield 6, 7, 8 and 9, but with different probabilities: the coin method gives the four outcomes in proportions of 1, 3, 3 and 1, while the yarrow method makes young yin more likely than young yang and old yin less likely than old yang. Both are still in use. Pick one and stay with it.
An honest note
Casting is a practice for stating a question clearly and then thinking it through from a fixed reference point. For how to frame the question before you cast, see how to ask the I Ching a question. It is not a prediction mechanism and it guarantees nothing. For medical, legal, financial or other major decisions, consult a qualified professional.
常見問題
- Do I have to use antique Chinese coins?
- No. The method only needs three coins with two distinguishable faces, and you must decide in advance which face counts as 2 and which as 3. Antique coins are a convention, not a requirement.
- What if there are no changing lines?
- If all six lines come out as 7 or 8 there are no changing lines and no resulting hexagram. You read only the primary hexagram's text and image. That is a normal outcome, not a reason to recast.
- 同一個問題可以重擲嗎？
- The usual practice is one casting per question. Recasting because you dislike the result removes the reference point. If you want another angle, rewrite the question more concretely and cast on that.
Practise with an app
To follow the rules without coins, the YiJian web version is free and needs no login: it casts hexagrams and holds all 64 of them. YiJian is an iPhone course app that teaches you to read the I Ching; it is currently in App Store review and not yet released.