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Grease Interceptor Sizing

Right Sizing

Many plumbing codes focus on either flow rate or liquid volume to size a grease interceptor, which can lead to undersizing or oversizing. Schier considers both flow rate and grease production to determine the capacity of the interceptor and its recommended pumpout frequency.

A correctly sized grease interceptor reduces maintenance costs for restaurants as well as the chance of a messy and costly clog/backup. Right sizing is critical in choosing the correct grease interceptor, and we’ve got it down to a science. It’s called Grease Production Sizing Method (GPSM).


Introduced by Schier in 2012, GPSM calculates how much grease a restaurant is likely to produce to ensure the grease interceptor has enough capacity to allow for a realistic and affordable pumpout frequency.

GPSM has been used to size more than 100,000 restaurant grease interceptors, adopted by several municipalities, published in the 2016 edition of the ASPE Plumbing Engineering Design Handbook and now powers our Grease Monkey® sizing app.




For more details on how to size a grease interceptor using GPSM, get our free Grease Production Sizing eBook.



Grease Monkey® guides you through the important aspects of sizing and produces a plans-ready sizing report using GPSM. Once you receive your recommended interceptor, you can opt-in to our complimentary GM CHECK service in which our sizing experts double-check your work and confirm local code approval for your grease interceptor installation.

GM CHECK services:

  • SPOT CHECK - Consult with a specialist regarding general guidance, non-jurisdiction related sizing questions, or product inquiries.

  • JURISDICTION CHECK - An in-depth review with a specialist that covers jurisdiction specific questions or when you're ready to confirm jurisdiction compliance.

Additional Grease Monkey Features:

  • Easy-to-use interface

  • The ability to save and modify previous sizings

  • Produces PDF plans-ready detail diagram and sizing calculations, perfectly sized for placement on your construction documents

  • Accommodates local jurisdictional requirements including Miami, Illinois, Wisconsin, Oregon, and more!

  • GM CHECK service facilitated by Schier’s sizing experts…all for free!

Grease Monkey® is a registered trademark of Schier Products Company

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