Grease Trap Sizing Calculator
Estimate peak demand using the assumptions below. This screening model is not a verified IPC/UPC fixture-sizing calculation or an installation approval.
Method and worked example
The current screening model multiplies seats × meals per seat per hour × peak hours × 5 assumed gallons per meal × a 2.5 planning factor, then divides by peak minutes. Each selected equipment checkbox adds a 1.25 multiplier. The result is rounded up to the displayed size bands. The IPC/UPC selector does not change this calculation.
Example: 50 seats × 1 meal × 2 hours × 5 × 2.5 ÷ 120 minutes = 10.42 estimated GPM, rounded to 15 GPM. These are model assumptions, not a code-derived fixture calculation. The displayed capacity and cost figures are preliminary model outputs, not manufacturer specifications or supplier quotations.
Supply the authority with actual fixture volumes, drain-down times, connected equipment and the proposed listed device. Check the applicable sizing method and product rating before ordering. Austin’s official sizing guidance illustrates why local design review matters. Find city requirements · Understand pumping thresholds.
Establishment Details
Common Sizes
| Type | GPM | Cost |
|---|---|---|
| Small cafe | 7-10 | $250-$500 |
| Small restaurant | 15-20 | $400-$800 |
| Medium restaurant | 25-50 | $600-$1,500 |
| Large restaurant | 50-75 | $1K-$3K |
| High volume | 75-100 | $2.5K-$10K |
How It Works
IPC Method (Section 1003.3.4): Uses meals per peak hour multiplied by wastewater per meal (5 gal) and a 2.5 retention factor. Adjustments for dishwashers (+25%) and garbage disposals (+25%).
UPC Method (Section 1014): Sizes interceptors based on total fixture unit count and flow rate in GPM.
Find Your Local Requirements
Sizing is only part of the equation. Check your city's FOG regulations for permit, pumping, and inspection requirements.
Browse State Regulations