The Author's Own
Bach/Schilke Mouthpiece Equivalency Chart


Bach stated measurement in mm (decimal)

Curry measurement
(in decimal)

Laskey measurement
(in decimal)

Schilke equivalent mouthpiece

Schilke measurement
(in decimal)


17.00 (.670)





1.5 C

17.00 (.670)






16.30 (.642)






16.25 (.640)






16.20 (.638)






15.90 (.625)





Everybody's got their own chart for mouthpiece cup diameter equivalents, and now you have mine. Because of Bach's longevity in the marketplace, their early domination of the market, and the proclivity of other makers to copy what appears to be a labeling system, Bach mouthpiece sizes, even if you haven't played a Bach mouthpiece in years, are those to which we compare all others.

This should be easier, but Bach makes it hard. The Bach published measurements, in millimeters above, are taken from the Bach Mouthpiece Handbook, issued annually with a catalog of Bach/Selmer accessories. It is universally acknowledged that those measurements are all wrong. In the olden days, as the machine tools wore out, the mouthpieces would get bigger, and then revert to the smaller sizes when new tooling was installed. It apparently reached the point where the more common sizes were the worn out ones, rather than the specified ones, and the tooling for the mouthpiece was actually changed to reflect the more common larger cuttings, rendering the original specifications useless. Perversely, Bach refuses to remeasure the pieces now to publish accurate information and refuses to eliminate the obsolete specifications from their product information. No specs would be better than wrong specs, you'd think.

Then there is Bach's legendary inconsistency....

Both Mark Curry and Scott Laskey make and sell what they describe as precision copies of classic (early 60's) Bach mouthpieces. Please compare the Bach published measurements with those of Curry and Laskey, and then at least feign outrage at the continued inaccuracies of the Bach specifications. What I have done is taken published measurements of the Curry and Laskey copies of classic Bach mouthpieces and then match those with the Schilke mouthpiece with the closest cup diameter measurement. The last column is Schilke's published measurement for the Schilke mouthpiece that is the Bach equivalent in the adjacent column.

This is, in all likelihood, as precise as one is going to get in a Bach/Schilke equivalency chart because:

  • Mouthpiece manufacturers do not all measure the cup diameters at the same place on the cup, so as precise as the above appears, there may be differences in practice which arise from that measuring inconsistency. For example, I have a couple of Schilke 18 rims which have been threaded to fit different Giardinelli 1 cups. I figured this would work because the cup diameter, as measured and published by the respective manufacturers, of the Schilke 18 is 17.52 mm and the cup diameter of Giardinelli 1 is 17.50 mm. They did fit nicely, however, the Giardinelli cups were just the tiniest bit bigger than the Schilke 18 rim, when you would expect exactly the opposite to be the case based on the measurements.
  • The cup depth of the mouthpiece also makes a difference. Reviewing carefully the cup diameter measurements of the Schilke mouthpieces, it is clear that there is a difference in cup diameter when the mouthpiece is made up with the shallower cups. For example, the cup diameter of the Schilke 14, 14B, and 14C2 are 17.02 mm, the 14A4(c), 14A4a and 14A4x are slightly wider, at 17.09. The same thing is true with Schilke 12 and 15 mouthpieces.
  • Rim contour also makes a difference. The Schilke catalog reports on the Schilke 18 that "[t]he high point of the rim being nearer the center makes this mouthpiece feel much smaller." Is this true of the slightly smaller Schilke 17 as well? Some of the differences in the measurements between different mouthpieces of the same nominal size may in fact be attributable to the rim difference as much as the cup difference. See the Schilke 15 series, for example.

So, even though we attempt to measure in the thousandths of an inch or the hundredths of a millimeter, other variables limit how precise and valuable a purely numerical comparison can be.

Go play on the mouthpieces!


The Schilke Loyalist


© 1999 by James F. Donaldson
All rights reserved