I'm refurbishing a trumpet, and it needs a mouthpiece. The numbers and letters on those available seem to have no logic about them at all. Could someone explain what the differences are?

EDIT: and what those differences actually make playing wise?

  • I went on a similar journey for clarient and French horn mouthpieces. I suspect there is no logic but I’m not sure. Note that many players will keep their mouthpiece when they sell the instrument and use their own mouthpiece when they buy one. At the same time, especially for beginners, it’s nice when a mouthpiece is included. You might simply supply a mouthpiece recommended for beginners. May 9, 2023 at 13:56
  • 1
    Very closely related question: Naming convention for trumpet mouthpiece size.
    – Aaron
    May 9, 2023 at 14:19
  • Things for trumpet players to talk about on a break? (Sorry, couldn’t resist) May 9, 2023 at 15:57

1 Answer 1


What do the codes mean?

The details vary according to manufacturer, but they refer to the diameter and depth of the cup.

As an example, I've always played Bach brand mouthpieces. I started with a 7C, which has a (relatively) smaller diameter and shallower cup. Then I moved to a 3C, which has a wider diameter but similar cup depth. Bach gives a more detailed description of their mouthpieces and sizing at Bach Mouthpieces. 7C is a very standard model for a beginner, and 3C is very standard for a more advanced player, but, to quote the linked page:

Because no two players have the same lip or tooth formation, what is perfect for one player may be entirely unsuitable for another.

The site HSUTrumpets has a listing of mouthpiece manufacturers that includes links to their websites. Yamaha may be of particular interest, as, besides Bach, they are one of the major trumpet brands.

How does it affect playing?

Cup diameter

The narrower the cup, the smaller a player's aperture can be, and the tighter the embouchure needs to be. Someone with thicker lips, for example, might be more comfortable playing a wider mouthpiece. Or, someone who plays a lot of high notes might prefer a narrower one. Tone will tend to be mellower with a wider cup and brassier with a narrower one.

Cup depth

The differences here are similar. Someone with thinner lips might prefer a shallower cup. A deeper cup tends to mellow things out tone-wise. Shallower also corresponds to a shorter response time in making a sound. Shallower cups can ease high-note playing; lead trumpet players will often use shallow-cup mouthpieces.

  • So, letters are indicative of depth of cup - A being deepest, up to W most shallow (missing many letters between!). The '#' doesn't seem to have a lot of logic to it though. I have a couple of mouthpieces, and one won't even go into the tubing on the trumpet: I was hoping the number might reflect the o.d. of the mouthpiece entry end, but sadly, doesn't appear that way!
    – Tim
    May 9, 2023 at 14:28
  • 1
    @Tim The bore size is a separate issue, but the one that won't go into the trumpet sounds like it may not be a trumpet mouthpiece at all. Possibly a cornet or flugelhorn. It's also possible that the trumpet itself has a narrow bore, but mouthpieces are usually tapered to accommodate that.
    – Aaron
    May 9, 2023 at 14:33
  • Both fit into my 'main' trumpet, and, yes, the one I'm working on is an ancient French small bore, consequently only one will fit happily into that, but even then not very far - although it can still be tuned to Bb (with A=440Hz)
    – Tim
    May 9, 2023 at 14:38
  • Note, I've edited the question, to find out what those different dimensions actually mean in the real world of playing.
    – Tim
    May 9, 2023 at 16:53

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