Grease Trap Sizing Calculator

Size grease interceptors for commercial kitchens and food service establishments. Calculate capacity requirements based on fixture loads and code requirements.

System Configuration

Establishment Type

Interceptor Type

Code Requirements

Cleaning Frequency

Peak Load Factor (%)

Retention Time (min)

Storage Capacity (%)

Kitchen Fixtures

Kitchen Equipment

Dish Machine (Door Type)

5 GPM, 4 DFU

Dish Machine (Conveyor)

8 GPM, 6 DFU

Dish Machine (Flight Type)

12 GPM, 8 DFU

Pot Sink (3-Compartment)

4 GPM, 4 DFU

Pre-Rinse Sink

3 GPM, 2 DFU

Hand Sink

1.5 GPM, 1 DFU

Food Preparation

Preparation Sink

2.5 GPM, 2 DFU

Vegetable Sink

3 GPM, 2 DFU

Mop Sink

2 GPM, 2 DFU

Floor Drain (4")

2 GPM, 1 DFU

Floor Drain (6")

4 GPM, 2 DFU

Cooking Equipment

Wok Station

2 GPM, 2 DFU

Steam Table

1 GPM, 1 DFU

Coffee Machine

0.5 GPM, 1 DFU

Ice Machine

1 GPM, 1 DFU

How Grease Trap Sizing Works

Basic Sizing Formula

C = Q × T × S × F

• C = Required Capacity (gallons)

• Q = Flow Rate (GPM)

• T = Retention Time (minutes)

• S = Storage Factor (1 + storage %)

• F = Flow Rate Multiplier (code/peak load)

Flow Rate Calculation

Q = Σ(fixture GPM × count)

• Sum of all fixture flow rates

• Adjusted by peak load factor

• Modified by establishment type

• Code requirements applied

Retention Time Guidelines

• Gravity Units: 30 minutes minimum

• Hydromechanical: 1-3 minutes typical

• High Load: Consider longer retention

• Code Requirements: May specify minimum

Interceptor Type Selection Guide

Gravity Interceptors

• Best For: High flow rates, outdoor installation

• Capacity: 500-2000 gallons typical

• Maintenance: Monthly to quarterly

• Installation: Requires significant space

Hydromechanical Units

• Best For: Limited space, indoor use

• Capacity: 20-75 GPM typical

• Maintenance: Weekly to bi-weekly

• Installation: Under-sink or in-floor

Professional Sizing Guidelines

Establishment Types

• Fast Food: Higher grease output, frequent cleaning

• Full Service: Moderate load, standard sizing

• Cafeteria: High volume, peak load periods

• Hotel/Hospital: Consistent load, 24/7 operation

Best Practices

• Size for maximum anticipated flow

• Consider future expansion needs

• Follow local code requirements

• Plan for regular maintenance access

• Include venting and monitoring points

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Complete Your Commercial Kitchen Design

Grease trap sizing is crucial for commercial kitchen plumbing. Explore our related calculators for a comprehensive system design:

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