You picked up a trumpet mouthpiece and it says "Bach 7C" on the shank. Or maybe "Schilke 14A4a." Or "Yamaha TR-14D4." You have no idea what any of those numbers and letters mean — and you are not alone. Every trumpet player hits this wall eventually.
The frustrating part is that there is no universal standard. Every brand invented its own system. Some brands use numbers where lower means bigger. Other brands use numbers where lower means smaller. The same letter can mean cup depth in one brand and backbore taper in another.
This guide decodes all of it. By the end you will be able to look at any mouthpiece from any major brand and know what the model name is telling you — and what that means for how it plays.
If you want to skip straight to decoding a specific model, use the Mouthpiece Name Decoder — type in any model from any major brand and get an instant plain-English breakdown.
Why the Naming Systems Are Such a Mess
When Vincent Bach started making mouthpieces in the early 20th century, he created a numbering system that made sense to him. Other manufacturers came along later and created their own systems — sometimes deliberately different, sometimes just independently developed.
Nobody ever sat down and agreed on a standard. The result is that today:
- Bach 3 = large rim diameter
- Schilke 3 = very small rim diameter
- Yamaha 3 = does not exist as a standalone number — their scale runs 5 to 68
Same number. Three completely different sizes.
This is why the golden rule of mouthpiece comparison is: never compare model numbers across brands. Compare millimeter measurements.
Model numbers are labels. Millimeters are facts.
With that foundation in place, let us decode each system one by one.
The Bach Numbering System
Bach is the reference brand — the one everything else gets compared to. Understanding Bach first makes every other system easier to learn.
The number: rim inner diameter
The number in a Bach model name refers to the rim inner diameter — the opening of the cup where your lips go.
The scale runs counterintuitively: lower number = larger diameter.
| Bach number | Rim inner diameter (approx.) | Who it is for |
|---|---|---|
| 1 | ~17.00mm | Large lips, orchestral specialists |
| 1.5 | ~16.84mm | Standard orchestral size |
| 2 | ~16.76mm | Large-medium, orchestral/chamber |
| 3 | ~16.76mm | Medium-large, all-around workhorse |
| 5 | ~16.50mm | Medium, common step up from 7C |
| 7 | ~16.20mm | Medium-small, universal beginner size |
| 10 | ~15.90mm | Small, high register specialist |
| 10.5 | ~15.75mm | Very small, lead/commercial |
| 12 | ~15.50mm | Very small, specialized |
The 7C is the most common mouthpiece in the world — it ships with millions of student trumpets. The 3C is the most common "adult" or "upgrade" mouthpiece. The 1.5C is the standard orchestral size.
The letter: cup depth
The letter in a Bach model name refers to cup depth.
A = deepest. F = shallowest. C = standard (the middle).
| Bach letter | Cup depth | Tone character | Best for |
|---|---|---|---|
| A | Deepest | Warmest, darkest | Deep orchestral, tuba-like richness |
| B | Very deep | Warm, full | Orchestral, chamber music |
| C | Standard | Balanced | All-around, most common |
| D | Medium shallow | Brighter, more focused | Jazz, commercial |
| E | Shallow | Bright, cutting | Lead trumpet, commercial |
| F | Very shallow | Very bright, very focused | High-note specialist |
So a Bach 3C = medium-large rim + standard cup = the all-around workhorse.
A Bach 7C = medium-small rim + standard cup = universal beginner.
A Bach 3E = medium-large rim + shallow cup = jazz lead standard.
A Bach 1.5C = large rim + standard cup = orchestral standard.
The "W" suffix
Some Bach models have a "W" at the end — for example, Bach 3CW. The W means wider outer rim. The cup and inner diameter are the same as the non-W version, but the outer rim is broader, spreading lip contact over a wider surface. Some players find this more comfortable for long playing sessions.
Full Bach standard trumpet mouthpiece reference
| Model | Rim diameter (mm) | Cup depth | Best use |
|---|---|---|---|
| 1C | ~17.00 | Standard | Orchestral / large bore |
| 1.5C | ~16.84 | Standard | Orchestral standard |
| 1.5B | ~16.84 | Deep | Orchestral / dark tone |
| 2C | ~16.76 | Standard | Large-medium general |
| 3C | ~16.76 | Standard | All-around workhorse |
| 3B | ~16.76 | Deep | Warm jazz / orchestral |
| 3D | ~16.76 | Medium shallow | Jazz mainstream |
| 3E | ~16.76 | Shallow | Jazz lead / commercial |
| 5C | ~16.50 | Standard | Medium general use |
| 5B | ~16.50 | Deep | Warm medium |
| 7C | ~16.20 | Standard | Universal beginner/intermediate |
| 7E | ~16.20 | Shallow | Small lead |
| 10.5C | ~15.75 | Standard | High register / lead |
| 12C | ~15.50 | Standard | High note specialist |
The Schilke Numbering System
Schilke is the second-most referenced brand and the most common upgrade destination from Bach. The system is more precise than Bach — but it runs in the opposite direction for the primary measurement, which causes endless confusion.
The critical difference from Bach
In Schilke: lower number = smaller diameter.
In Bach: lower number = larger diameter.
This is not a subtle difference. A player moving from Bach 3C who picks up a Schilke 3 thinking they are in the same size range will find themselves on something dramatically smaller.
Schilke's four-part code
A full Schilke model name has up to four components. Most catalog models only show some of them because the others are assumed to be standard.
Example: Schilke 14A4a
| Position | Value | Meaning |
|---|---|---|
| First number | 14 | Cup diameter (larger = broader) |
| First letter | A | Cup volume (A=small/shallow, C=standard, E=large/deep) |
| Second number | 4 | Rim contour (1=roundest, 5=flattest) |
| Final letter | a | Backbore (a=tight, b=semi-tight, c=standard, d=medium large) |
When a Schilke model shows only a number — like "Schilke 14" — all other parameters are standard, meaning C cup, 3 rim contour, c backbore. The full code would be 14C3c, abbreviated to 14.
Schilke cup diameter scale
| Schilke number | Rim diameter (approx.) | Bach equivalent size |
|---|---|---|
| 6 | ~14.30mm | Much smaller than any standard Bach |
| 7 | ~14.60mm | Smaller than Bach 12 |
| 10 | ~15.40mm | Roughly Bach 12 area |
| 11 | ~16.20mm | Roughly Bach 7 |
| 12 | ~16.30mm | Between Bach 7 and 5 |
| 13 | ~16.48mm | Roughly Bach 5 |
| 14 | ~16.76mm | Roughly Bach 3 |
| 15 | ~16.84mm | Between Bach 3 and 1.5 |
| 16 | ~16.84mm | Roughly Bach 1.5 |
| 17 | ~17.00mm | Roughly Bach 1 |
| 18 | ~17.15mm | Larger than Bach 1 |
Schilke cup volume letters
Unlike Bach where the letter refers to cup depth directly, Schilke uses cup volume — a combination of depth and shape.
| Schilke letter | Cup volume | Rough Bach equivalent depth |
|---|---|---|
| A | Small (shallow) | Between Bach D and E |
| B | Medium-small | Roughly Bach D |
| C | Standard | Roughly Bach C |
| D | Medium-large | Roughly Bach B |
| E | Large (deep) | Roughly Bach A |
Schilke rim contour numbers
| Number | Rim shape |
|---|---|
| 1 | Roundest |
| 2 | Semi-round |
| 3 | Standard (most common) |
| 4 | Semi-flat |
| 5 | Flattest |
Most Schilke mouthpieces use the standard rim (3). The 4 appears in the famous 14A4a — that semi-flat rim is part of what makes the lead mouthpiece feel efficient for high register work.
Schilke backbore letters
This is the most complete backbore documentation of any major manufacturer:
| Letter | Backbore type | Effect |
|---|---|---|
| a | Tight | More brilliance and control, more resistance, helps upper register |
| b | Semi-tight | Between tight and standard |
| c | Standard | Balanced — the default |
| d | Medium large | Darker, more volume, less resistance |
| x | Large | For piccolo trumpet |
| z | Extra-tight | Maximum resistance and focus |
The legendary Schilke 14A4a — decoded
This is the most famous lead trumpet mouthpiece in the world. Here is what each character means:
- 14 — medium-large cup diameter (roughly Bach 3 size area)
- A — small/shallow cup volume
- 4 — semi-flat rim contour
- a — tight backbore
Combined: medium-large rim opening, shallow cup, slightly flat rim, tight backbore. Everything optimized for upper register efficiency and brightness. The tight backbore and shallow cup work together to reduce the air column required to slot high notes. The semi-flat rim (4) sits efficiently against the lip without the grip of a very round rim.
The Yamaha Numbering System
Yamaha produces some of the most consistently manufactured mouthpieces available at any price point. Their naming system is completely different from both Bach and Schilke.
The number: inner diameter on a 5–68 scale
Yamaha uses a numeric scale from 5 to 68 to express inner diameter. Higher number = broader rim.
| Yamaha number | Rim diameter (approx.) | Comparable Bach rim |
|---|---|---|
| 7 | ~14.60mm | Smaller than Bach 12 |
| 9 | ~15.10mm | Bach 12 area |
| 11 | ~16.20mm | Bach 7 |
| 13 | ~16.48mm | Bach 5 |
| 14 | ~16.76mm | Bach 3 |
| 16 | ~16.84mm | Bach 1.5 |
| 17 | ~17.00mm | Bach 1 |
The critical warning: Yamaha cup letters run opposite to Bach
This catches players constantly.
In Bach: A = deepest cup, F = shallowest
In Yamaha: A = shallowest cup, E = deepest
| Yamaha letter | Cup depth | Bach equivalent letter |
|---|---|---|
| A | Shallow | Roughly Bach E |
| B | Medium shallow | Roughly Bach D |
| C | Standard | Roughly Bach C |
| D | Medium deep | Roughly Bach B |
| E | Deep | Roughly Bach A |
So a Yamaha 14A4 = medium-large rim, shallow cup = lead mouthpiece. Looks like it should be a deep warm mouthpiece if you are reading it like Bach. It is the opposite.
A Yamaha 14D4 = medium-large rim, medium-deep cup = all-around mouthpiece. Closest equivalent to a Bach 3C.
Yamaha rim contour numbers
Same scale as Schilke: 1 = roundest, 5 = flattest. Most standard Yamaha models use 4.
Yamaha backbore letters
| Letter | Backbore |
|---|---|
| a | Narrow |
| b | Semi-narrow |
| c | Standard |
| d | Medium wide |
| e | Wide |
The TR prefix
Yamaha uses "TR" before some model names to designate trumpet, distinguishing from cornet (CN) and flugelhorn (FL) models. TR-14D4 is a trumpet mouthpiece. The TR is sometimes omitted in casual reference.
Bobby Shew signature models
Yamaha produces Bobby Shew signature mouthpieces — "Bobby Shew Jazz" and "Bobby Shew Lead." These are named descriptively rather than by the standard number-letter code. The Jazz model is a medium cup, the Lead model is shallow. Both use the standard Yamaha shank.
The Warburton System
Warburton is fundamentally different from every other brand covered here. It is a modular system — you buy the rim and cup as separate pieces and combine them.
Why modular exists
The logic: your embouchure adapts to your rim. Changing your rim means weeks of adaptation. Changing your cup depth or shape does not require nearly as much adaptation. So Warburton lets you keep the same rim and swap cups as your playing demands change.
A player who plays orchestral gigs and lead trumpet gigs can own one Warburton rim and two cups — a deeper cup for orchestra, a shallow cup for lead — and switch cups between jobs. Total cost: one rim + two cups, rather than two complete mouthpieces.
The rim number
| Warburton rim | Rim diameter (approx.) | Bach equivalent |
|---|---|---|
| 2 | ~17.00mm | Bach 1 area |
| 3 | ~16.84mm | Bach 1.5 area |
| 4 | ~16.76mm | Bach 3 area |
| 5 | ~16.50mm | Bach 5 area |
| 6 | ~16.20mm | Bach 7 area |
| 7 | ~15.90mm | Bach 10 area |
| 8 | ~15.75mm | Bach 10.5 area |
Lower rim number = larger diameter. Same direction as Bach.
The cup code
| Cup code | Depth/type | Best for |
|---|---|---|
| M | Medium (standard) | All-around, general use |
| D | Deep | Orchestral, warm tone |
| MD | Medium deep | Between standard and deep |
| S | Shallow | Jazz, commercial |
| SV | Screamer (very shallow) | Lead trumpet, high register |
| ES | Extra shallow | Extreme high register specialist |
Reading a Warburton model
Warburton 4MD = Rim 4 (medium-large, Bach 3 area) + medium-deep cup = warm all-around mouthpiece
Warburton 7SV = Rim 7 (medium, Bach 10 area) + screamer cup = classic lead setup
Warburton 3M = Rim 3 (large, Bach 1.5 area) + medium cup = orchestral mouthpiece
The modular system means any rim number can pair with any cup code. There are dozens of possible combinations from a relatively small number of parts.
Other Brands at a Glance
Denis Wick
Denis Wick uses a straightforward numbering system: lower number = larger size, similar logic to Bach. Numbers run roughly 1 (largest) through 6 (smallest) for standard trumpet models.
| Denis Wick | Approximate Bach equivalent |
|---|---|
| 1 | Bach 1.5C area |
| 2 | Bach 3C area |
| 3 | Bach 5C area |
| 4 | Bach 7C area |
| 5 | Bach 10C area |
Denis Wick dominates the UK brass band market and is the go-to brand for cornet players. Their trumpet mouthpieces are well-regarded for orchestral playing. The "Heritage" line is their premium series.
GR (Gary Radtke)
GR uses numbers that approximate the inner diameter in hundredths of inches:
- GR 64 ≈ .640" ≈ 16.26mm → Bach 7 area
- GR 65 ≈ .650" ≈ 16.51mm → Bach 5 area
- GR 66 ≈ .660" ≈ 16.76mm → Bach 3 area
- GR 67 ≈ .670" ≈ 17.02mm → Bach 1–1.5 area
- GR 67.4 ≈ .674" ≈ 17.12mm → Bach 1.5C area
Cup depth follows with a letter: M = medium, L = large/deep, S = shallow, XL = extra large.
GR mouthpieces are premium-priced and manufactured to very tight tolerances. Players consistently report excellent slotting and intonation. Used by many professional orchestral players.
Monette
David Monette uses a B-series naming system:
- B2, B4, B5, B7 — the number roughly corresponds to rim diameter (B2 = larger, B7 = smaller)
- S1, S2, S3 — resistance/backbore variant
- L, LS, SL — cup depth variants
Monette mouthpieces are designed to work as a system with Monette trumpets. They are among the most expensive mouthpieces made ($400–$1,500+). Used by several major orchestral soloists. Not recommended for players who are not also using a Monette instrument — the system optimization does not transfer.
The Most Important Rule: Use mm, Not Model Numbers
After reading all of the above, the single most important thing to take away is this:
Model numbers are brand-specific labels. Millimeters are the universal language.
When you want to compare mouthpieces across brands, do not compare the numbers in the model names. Compare the actual mm measurements. A Bach 3C and a Schilke 14C are roughly equivalent not because they both have a 3 or C in the name — one of those overlaps is coincidence — but because their measured inner diameters and cup depths are close to each other.
Equivalent Finder ranks similar mouthpieces using normalized mm data from our database, not brand codes. Compare shows two models side by side with notes. That is why results are more reliable than static charts that only list model names next to each other.
How to Decode a Mouthpiece You Found With No Markings
Old mouthpieces lose their engravings. Vintage pieces have worn shanks. You might find a mouthpiece in a case with no legible markings at all. Here is how to identify it:
Step 1 — Measure the rim inner diameter
Use a digital caliper. Measure the inner opening of the cup. Round to two decimal places. This is your primary identifier.
Step 2 — Estimate the cup depth
You cannot measure cup depth easily without specialized tools. Instead, hold the mouthpiece up to a light source and look through it from the rim end. A deep cup will look dark and hollow. A shallow cup will show the throat opening clearly. This gives you a rough category: deep, standard, or shallow.
Step 3 — Note the shank shape
Is it a standard trumpet shank? Or is it shorter (cornet) or longer/larger (trombone)? This tells you what instrument it is designed for.
Step 4 — Search by measurement
Use the database to filter by rim diameter and browse matches. Use Equivalent Finder if you have one known reference model. Identify can help narrow unknown pieces when you have partial info.
Step 5 — Check the backbore visually
Look at the shank end. A tight backbore opens slowly and narrowly. An open backbore opens wide quickly. This is a rough qualitative check — do not try to measure this without specialized equipment.
Quick Reference: The Most Common Mouthpieces Decoded
Here are the most searched mouthpiece model names decoded in plain English:
Bach 7C — medium-small rim, standard cup. The universal beginner mouthpiece. Balanced in every spec, forgives technique inconsistencies, works for most students and intermediate players.
Bach 3C — medium-large rim, standard cup. The all-around adult workhorse. Most widely recommended "upgrade" from the 7C. Works for jazz, concert band, general practice.
Bach 1.5C — large rim, standard cup. The orchestral standard. Big sound, full low register. Requires a developed embouchure to play efficiently.
Bach 3E — medium-large rim, shallow cup. Classic jazz lead configuration. Brighter tone, easier upper register access. The trade-off is a thinner sound in the low and middle register.
Schilke 14A4a — medium-large rim, shallow cup, semi-flat rim contour, tight backbore. The most famous lead mouthpiece in the world. Everything optimized for the upper register.
Yamaha 14D4 — medium-large rim, medium-deep cup. The "D" does not mean deep in Yamaha language — it means medium-deep, roughly equivalent to a Bach C cup. A solid all-around mouthpiece.
Yamaha 14A4 — medium-large rim, shallow cup. Lead mouthpiece. The "A" in Yamaha means shallow — opposite to Bach where A means deep.
Warburton 4MD — medium-large rim, medium-deep cup. A warm all-around mouthpiece, popular with players who want slightly more depth than a standard M cup.
Warburton 7SV — medium rim, screamer cup. One of the most popular lead setups on the market. The small rim and very shallow cup combine for maximum upper register efficiency.
What to Do Next
You now have the complete decoder for every major mouthpiece brand. No more guessing what a model name means. No more assuming a Schilke 3 is in the same range as a Bach 3.
Decode any specific model name right now:
→ Mouthpiece Name Decoder — type in a model from any major brand, get a plain-English breakdown.
Find the equivalent in another brand:
→ Equivalent Finder — ranked matches from measured specs.
Read the full cross-brand comparison guide:
→ The Complete Cross-Brand Trumpet Mouthpiece Comparison Guide
Understand how anatomy and choosing strategy fit together:
→ The Complete Guide to Trumpet Mouthpieces
Not sure what to try next?
→ Mouthpiece Advisor — short questionnaire, specific suggestions.
Part of the mouthpiececomparator.com series. Related: Complete Guide · Cross-Brand Comparison · Blog index.