How do I size a grease trap for a 3-compartment sink?
The common fixture method: multiply each sink bowl's length x width x depth (inches), times the number of compartments, and divide by 231 to get gallons. Take 75% of that (the drainage load), divide by a 1-minute drainage period to get GPM, and round up to the next standard PDI grease-trap size (e.g., 20, 35, 50 GPM). This tool does that. Large operations use a gallon-capacity grease interceptor sized differently - your local sanitary district sets the method.
What size grease trap do I need?
For a typical 3-compartment sink, small indoor grease traps commonly land at 20-50 GPM by the fixture method. But requirements vary a lot: many jurisdictions mandate a large exterior grease interceptor (500-2,000+ gallons) sized by seats, flow, or a local formula. Always confirm the required method and size with your local plumbing/sewer authority before you build.
Grease trap vs. grease interceptor - what's the difference?
A grease trap (or 'grease recovery device') is a small point-of-use unit rated in GPM, sized by the fixtures draining into it - what this calculator estimates. A grease interceptor is a large in-ground/exterior tank rated in gallons, sized for the whole kitchen by local code. Many cities require the interceptor for a full commercial kitchen.
Does this meet code?
It's a planning estimate using the standard sink-fixture method. Your local plumbing code and sanitary district set the required device type, sizing method, and minimum size - confirm with them before purchasing or plumbing.