Grease Interceptor Size Estimator

Who it's for: Plumbing designers, commercial kitchen contractors, estimators, and facility teams.

This Grease Interceptor Size Estimator page is designed as a practical planning resource for plumbing designers, commercial kitchen contractors, estimators, and facility teams.

Calculator Inputs

Next Steps

Start with realistic fixture/demand assumptions and validate against code methods.
Check pressure, flow, or slope implications before locking design direction.
Record assumptions for permit and field coordination follow-through.

Worked Example

Worked example: use your real project inputs, run at least one conservative scenario, and compare outputs against one related calculator before finalizing direction.

Detailed Explanation

Supports a flow-times-retention method and a fixture-volume method for quick planning comparisons. Applies kitchen load factor assumptions (light, medium, heavy) to adjust base volume. Maps estimated gallons to the nearest common standard interceptor size.

Supports a flow-times-retention method and a fixture-volume method for quick planning comparisons.
Applies kitchen load factor assumptions (light, medium, heavy) to adjust base volume.
Maps estimated gallons to the nearest common standard interceptor size.

Common Mistakes

Ignoring run length or pressure constraints when sizing lines.
Using generic fixture assumptions that do not match actual use profile.
Skipping local plumbing code verification.

FAQ

Start with flow x retention for a quick estimate, then compare with fixture-based mode when sink geometry is available.

Kitchen type applies a factor to estimated volume so heavier grease loads produce larger recommended sizes.

No. This is a planning estimator only and local codes and authorities may require specific sizing procedures.

Manufacturers may use different assumptions, performance criteria, and approved sizing methods than this MVP estimator.

When to Call a Professional

Call a licensed plumber when outputs influence final installation decisions or permit submissions.

Related Calculators

Fixture Flow Rate Calculator

Estimate total and diversified fixture flow demand in GPM so plumbing teams can plan supply sizing and evaluate expected peak usage patterns.

Sewer Pipe Capacity Calculator

Estimate full-flow sewer capacity and velocity using Manning-based assumptions for quick drainage planning checks.

Pipe Size Calculator

Estimate nominal supply pipe size from fixture count, run length, and material assumptions to support quick planning before detailed code checks.

Conclusion

Use this estimate to improve planning speed and communication, then validate final values against code and manufacturer data.

About This Calculator

About this calculator: Plumbing designers, commercial kitchen contractors, estimators, and facility teams.

Educational and planning use only. Verify final values with licensed professionals.

Written by BuildCalcTools Team - Plumbing planning guidance.

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