Not all Flutes of course are created equal when it comes to volume.
So how do the following rank in terms of creating a loud Flute and why?
Bore diameter
embouchure
finger hole size
depth of embouchure and finger holes and undercutting
something else? 
Ben Shaffer
See that knob on the end? 
didnāt get the knobs on my Flutes , they were extra 
probably rules out the foot pedal attachment too then
Itās very simple: cubic volume of flutes is inversely proportional to bank account balance.
Weāve got many experts on board.
I misread that as āCubitt volumeā!
The blow hole (or the whole headjoint?) makes the biggest impact on everything on the flute, volume too.
Iāve tried some friendsā headjoints on my flute body, the difference was really impressive.
Yes, Iāve heard people say that, but personally I think that it is all in your head.
OK, weāve had some Jokes 
, but do we have anyone that is actually knowledgeable about this? 
bit complex for this vehicleā¦
Not sure what youāre looking for, Ben. Youāve hit all the high points except the most important: technique.
Actually there is a reason for my asking this question. Ive got a Flute that is on the rather quite side. Its a blackwood Flute, has a pretty standard embouchure, has fairly large size finger holes and the Flute diameter may be enlarged Iām guessing. I canāt help but think the Flute properly tweaked can be made to have increased volumeā¦ That said what direction would you take to accomplish this firstā¦reream the Flute, undercut or even enlarge the holes, recut the embouchure?
OK, Ben, hereās my experience. I have a Tony Dixon delrin flute. An early model, with four sections, no tuning slide. Clearly based on a small bore, small holed Rudall design, complete with two āventā holes in the foot. It has a mirror-like polish to the body bore. The Embouchure hole is relatively enormous. . .easily as large as my student model Bundy Boehm flute with a very modern cut. The amount of volume that can generated with this flute is startling, considering how small are the tone holes. Another peculiarity is the roughness of the head-joint bore, almost suffering from ātear-outā type blemishes. . .perhaps an attempt to create a little more ācharacterā or ācolorā to the tone.
Bob
Ben,
Youāve hit on a topic that is quite complex and has been hashed out and argued about on this forum many different times.
Super basic assumptions: Prattens are louder than Rudalls. Problem is this does not hold true as a hard fast rule. The larger the bore usually the more volume potential. But there are so many other factors: the player, how the flute is blown, how the flute works. A certain player playing a smaller bored Rudall may play very loudly, cutting through and over a Pratten player. I play a smaller bored flute but am plenty loud.
Thereās a start for you. My 3 year old needs meā¦
The rank is as follows:
player
player
player
player
player
player
bore size
embouchure size
The tone holes donāt play into that too much, Firth&Pond flutes can be driven very loud despite their small holes, because they usually have big bores. They just ābreakā earlier (i.e. into the high octave) due to the smaller holes providing less exit space for the chased air molecules (I think. not a phycicist tho).
The bore has a huge influence on everything, but I assume that everything is right on our imaginary flute. If the bore is wrong, a big volume/presence canāt be achieved due to several funny things that happen (in the wrong bore), making it difficult for the air column to stay in a stable state. That is the reason why most cheap old german flutes and pakistani flutes donāt workā¦the bore is wrong. It really takes something to make an embouchure hole bad, if the bore is right, a simple hole without any undercutting already works nice and gives you honk on the low notes. Undercutting is mostly necessary for forming the tone then (and it influences the response of low E).
great info Gabriel!
so German and Paki Flute donāt work because the Bore is to small or because the bore is wrong relative to?
The larger the bore
itās actually the larger the holes mostly. Thatās why they started undercutting the holes, because otherwise they were too large to cover.
embouchure has a lot to do with it, too.
as does the bore size at the foot of the flute. thereās a critical taper at the foot joint. One of Prattenās things, though Quantz first came up with it.
Thatās why Nicholson was so popularā¦he was LOUD for his timeā¦and it was his father of the same name who came up with the idea of the large tone holesā¦and why Boehm took them up.
hope this helps
The biggest effect Iāve seen on volume is standing up straight and keeping your chin up. I focus on something in the distance to keep my head up, as I have a nasty tendency to look toward the ground when I concentrate, and this brings the head down. Keep the elbows up and the chin high and see if that doesnāt make a difference. When you play flute, your entire body becomes part of the instrument. You wouldnāt buy a bent flute, so donāt encourage a slouched body.
Check out my avatar. Thatās me doing it WRONG. 