How to Calculate Grease Trap Sizing
What is Grease Trap Sizing?
Grease Trap Sizing Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Trap Size (GPM) = Flow Rate from Fixtures / Retention Time
Step-by-Step Guide
- 1Count fixture units connected, calculate peak flow rate
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
3 sinks at 2 GPM each, 2-minute retention
Result
Trap = 6 GPM flow → use 10 GPM trap
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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