Waking Spirit Productions
Vance Pennington - Flute Maker
Koko Waking Spirit Flutes

Frequently Asked Questions
Length to Bore Ratios


I am new to flute making and have read somewhere on the internet that the ideal length to bore ratio is 18:1. Am I correct in assuming that if I use a 1 inch bore, the sound chamber will be 18 inches in length?


Sadly, you are not correct! The ratio of 18:1 is an acceptable value BUT this value is only a part of the whole equation. The value of the K2 (formed at the embouchure or TSH) and the length of the K1 (formed at the foot of the flute) have to be taken into consideration when arriving at the best length to bore ratio. Doing such a calculation arrives at an ideal length to bore ratio of 24:1.  However, this does not mean you should create a flute with a 1 inch bore to be 24 inches in length. Both the K1 and the K2 form only when the flute is played so the physical flute body of the sound chamber will be shorter. For example, a flute with 1 inch bore, in the key of C, will be between 21 and 22 inches in length depending on the size of the TSH/embouchure the flute maker intends to create. It is complicated but this is something all flute makers should know and understand if they are to create quality instruments!