21-String Guzheng Tuning & Modulation Guide: D Major, G Major, C Major & F Major Yanzhu Bridge Position Chart (2026)

The standard 21-string Chinese Guzheng (古筝) spans four complete pentatonic octaves from the deepest wound copper-steel bass string #21 (`D2 = 73.42 Hz`) closest to the player's body up to the highest treble string #1 (`D6 = 1174.66 Hz`). Unlike fretted instruments that change key via finger placement or a capo, the Guzheng modulates between traditional keys—such as D Major (`1=D`), G Major (`1=G`), C Major (`1=C`), F Major (`1=F`), and A Major (`1=A`)—by physically sliding specific movable bridges (Yanzhu / 雁柱, literally "wild-goose pillars") left or right across the Paulownia soundboard. Use the interactive modulation calculator below alongside our Online 21-String Guzheng Tuner and 440Hz/442Hz Orchestral Tuner to see which Yanzhu bridges to shift and verify all 21 target frequencies in Hertz.

Master 21-String Guzheng Frequency & Jianpu Chart (D Major, G Major, C Major & F Major)

In standard Chinese conservatory pedagogy, Guzheng strings are numbered from #1 (the thinnest, highest-pitched treble string farthest from your body, `D6 = 1174.66 Hz`) to #21 (the thickest copper-wound bass string closest to your body, `D2 = 73.42 Hz`). Every five strings complete one full Gong-Shang-Jue-Zhi-Yu (宫商角徵羽) pentatonic octave (`Do - Re - Mi - Sol - La`, or `1 - 2 - 3 - 5 - 6` in Numbered Musical Notation / Jianpu). Compare all 21 strings across the four primary repertoire keys below, and use our Online 21-String Guzheng Tuner for hands-free sustain-lock calibration:

Acoustic Mechanics of Yanzhu (雁柱) Bridge Modulation & Circle of Fifths Logic

Why can a 21-string Guzheng switch seamlessly between five different pentatonic keys just by sliding four bridges at a time, without touching the tuning wrench inside the right-hand tuning box? The secret lies in how the Circle of Fifths interacts with a 5-note anhemitonic pentatonic scale (a scale containing major seconds and minor thirds, but zero semitones):

• Modulating Down a Fifth (1=D → 1=G → 1=C → 1=F): In D Major (`D - E - F# - A - B`), the third scale degree (`Mi / 3`, which is `F#`) sits just one semitone below the root of the subdominant key (`G`). Raising all four `F#` strings (#4, #9, #14, #19) by +100 cents to `G` transforms the scale pitches into `D - E - G - A - B`—which is the exact pitch collection of G Major Pentatonic (`G - A - B - D - E`)! Starting from G Major, raising the new third scale degree (`B` on strings #2, #7, #12, #17) by +100 cents to `C` produces C Major Pentatonic (`C - D - E - G - A`). Raising `E` (#5, #10, #15, #20) by +100 cents to `F` then yields F Major Pentatonic (`F - G - A - C - D`).
• Modulating Up a Fifth (1=D → 1=A): Conversely, to modulate from D Major (`D - E - F# - A - B`) to the dominant key of A Major (`A - B - C# - E - F#`), lower the four `D` strings (#1, #6, #11, #16, and #21) by -100 cents to `C#` by sliding their Yanzhu bridges 1.5 cm to 2.5 cm to the LEFT (away from the YueShan bridge).
• Physical Distance per Semitone on the Soundboard: Because vibrating string length $L$ between the right fixed bridge (YueShan) and the movable Yanzhu bridge increases progressively from roughly 42 cm on String #1 (`D6`) to over 132 cm on String #21 (`D2`), a +100 cent semitone shift ($L_{\text{new}} \approx L_{\text{old}} \times 0.9439$) requires only a 1.2 cm to 1.6 cm rightward bridge slide in the high treble register (#2–#5), compared to a 2.2 cm to 3.2 cm slide in the low bass register (#17–#20).

Step-by-Step Guzheng Tuning & Bridge Safety Protocol

1. Calibrate the Green Anchor Strings First (#8 A4 = 440 Hz or 442 Hz): Before sliding any bridges for modulation, open our Online Guzheng Tuner and pluck String #8 (`A4 = 440.00 Hz` or `442.00 Hz`). Once String #8 is locked within ±1.5 cents, calibrate the remaining octave A strings (#3 `A5 = 880 Hz`, #13 `A3 = 220 Hz`, #18 `A2 = 110 Hz`) using the square tuning wrench inside the right headbox.
2. Lift Slightly Before Sliding Yanzhu Bridges: Never drag a Yanzhu bridge forcefully across the bare Paulownia soundboard under full string tension, as the bone or rosewood base can score the wood grain and cause the bridge to tip forward. Use your left index and middle fingers to lift the string upward by 3 mm right next to the bridge saddle to relieve downward pressure, while your right hand slides the Yanzhu base smoothly to its new position.
3. Settle String Friction Over the Bridge Groove: Because a Guzheng string passes continuously over both the movable Yanzhu bridge and the fixed YueShan bridge, sliding a Yanzhu bridge to the right increases tension primarily on the right-hand playing segment while leaving the left non-playing tail slightly slacker. After moving a bridge, press down firmly on the left side of the string (just as you would for a vibrato or pitch bend) once or twice to equalize tension across the bridge groove before checking the final Hertz reading on the microphone tuner.