Flute layout calculator

You know nothing about making a flute? Good — this page is written for that. Three modes plus Carnatic: bamboo bansuri, PVC bansuri, murali (end-blown), and venu (8-hole Carnatic, side-blown). Pick a key, get tube size, mouth or labium placement, finger-hole marks, diameters, and a maker workflow.

Playing map for this room’s bansuri: Sa = top three finger holes covered (Eastern). Carnatic venu uses Sa = top two closed — see Carnatic venu. Jump to the calculator. End-blown path: The murali.
Numbers are starting marks. Finish by ear (or with Listen). Eye protection on. Never heat or burn PVC — toxic fumes; drill and file only.

Anatomy of a side-blown basuri

Imagine a hollow bamboo tube. One end is plugged (cork). Near that plug is the mouth hole (embouchure) you blow across. Along the top face are six finger holes. Many concert flutes add a seventh pancham (tuning) hole offset to the side near the open foot.

  • Top / cork end — closed with cork or rubber so the air column starts at a fixed place.
  • Embouchure (mouth hole) — oval hole you split air across. Size and undercutting change response a lot.
  • Inner diameter (ID / bore) — hollow width inside. Bigger bore → bigger sound, more air, larger holes.
  • Wall thickness — bamboo wall. Affects hole “chimney” depth and how sharp edges feel.
  • Outer diameter (OD) — roughly ID + 2× wall. Your fingers wrap the OD.
  • Finger holes 1–6 — numbered from the lips toward the foot. Hole 1 is closest to the mouth hole.
  • Hole 7 / pancham — side hole that helps middle Pa speak cleanly; often drilled last and offset.
  • Foot / open end — open tip. Shortening it raises the all-closed pitch.

Side-blown modes (bamboo + PVC) use a cork or end-cap and a wall embouchure. Murali mode uses an end-blown duct — see modes and The murali.

Bamboo · PVC · murali · venu

Bamboo bansuriPVC bansuriMuraliCarnatic venu
Blow Across side mouth hole Same (side-blown) Into the tip (fipple / duct) Across side mouth hole
Tube Seasoned bamboo Sch.40 PVC + end cap Bamboo (or PVC with a carved block) Bamboo (~14″ class common)
Holes 6 + optional pancham Same craft % 6 fingers (no pancham) 8 in a line (7 used daily)
Sa Top 3 closed Top 3 closed By ear / folk Top 2 closed
Best for This room’s path Cheap prototypes Easier first noise Carnatic / south Indian

Play guide: Carnatic venu.

How pitch works (beginner physics)

A bansuri behaves like an open tube: air vibrates from the embouchure to wherever the tube “ends” acoustically — the open foot, or the first open finger hole.

Rough rule (ideal open pipe):

sounding length ≈ speed_of_sound ÷ (2 × frequency)

Higher note → shorter sounding length → hole closer to the lips. That is why hole 1 (Ma) sits nearer the mouth than hole 6 (Dha).

What “key” means on a shop bansuri

  • C Natural medium (common beginner): three-hole Sa ≈ C5 (~523 Hz at A=440). All six closed, soft air ≈ G4 (lower Pa).
  • Bass charts: same letter names but roughly one octave lower (4th-octave Sa).
  • Indian colour names: White-1 = C, Black-1 = C♯, White-2 = D, … (Safed / Kali series).

Makers often cut length for Pa first (all holes closed), then drill upward: Dha → Ni → Sa → Re → Ga → Ma, enlarging as they listen. The calculator prints finished mark positions so you can mark all at once — still enlarge gradually.

Calculator

Bamboo/PVC hole marks use craft percentages of tube length (FluteMate-style). Murali remaps those ratios from the labium / window (voicing edge). Acoustic “hint” lengths are a second opinion from open-pipe math.

Beginners: start with C Natural Medium.

Centre of embouchure, measured from cork end.

Three holes closed (side-blown). Filled from preset + A4.

Warmer air → slightly higher pitch.

Layout results

Hole Opens toward From top (mm) From top (in) From mouth (mm) Gap (mm) Target Ø (mm) Start drill (mm) Acoustic hint (mm)

From top = craft mark along the tube from the cork/cap end (use these to pencil the tube). Acoustic hint = open-pipe estimate from the mouth/labium — expect several mm of disagreement; trust the craft column for marking, then tune.

Hole sizes & mouthpiece

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Practical maker workflow

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Glossary

  • Labium / window — cutting edge of a murali / recorder fipple where the air sheet splits.
  • Windway — narrow duct that aims air at the labium.
  • Sch.40 PVC — common plumbing pipe schedule; ID is smaller than the “½″ / ¾″” name on the label.
  • ID — inner diameter of the bore (mm).
  • OD — outer diameter ≈ ID + 2× wall (or stamped on PVC).
  • Embouchure — lip shape + the side mouth hole (bansuri).
  • Cents — 1/100 of a semitone. Tuners show how many cents sharp (+) or flat (−).
  • Equal temperament — Western piano spacing (twelfth-root-of-two). Good enough to place holes; raga intonation is finer.
  • Undercutting — bevelling the inside of a hole to change tone/pitch without moving the mark.
  • Meend — glide; needs flexible embouchure (side-blown) — advanced.

    • Limits, credits, safety

    • Bamboo tube presets summarise public FluteMate measurement charts. Hole % layout reverse-engineered from their published E Natural Bass mark list. PVC snaps those keys to common Schedule-40 bores. Carnatic venu uses eight denser marks across that span.
    • Murali marks remap the same musical ratios from the labium; fipple geometry is only hinted (window / windway sizes) — voicing is craftwork.
    • Venu play guide: Carnatic venu. Acoustic hints follow open-organ-pipe thinking. See also Flutomat.
    • Safety: eye protection; ventilated dust work. Bamboo: heated rods optional. PVC: never flame or melt. Adults only unless supervised.
    Choose a ready flute Carnatic venu Murali explainer Tune with Listen