Grease Trap Pumping Calculator | Biloxi & Gulfport, MS

How the estimate works

The calculator uses a planning formula that some municipal grease (FOG) programs publish for setting pump-out frequency. It is an estimate built on the 25% rule and rough industry averages, so treat it as a starting point and confirm it with a licensed, permitted grease hauler.

Grease the trap can hold before the 25% mark (lb) = capacity in gallons × 0.25 × 0.7 × 7.5 lb/gal. The 0.25 is the 25% rule; 0.7 assumes about 70% of that layer is grease and 30% settled solids; 7.5 lb is the approximate weight of a gallon of FOG. A 1,000-gallon interceptor works out to about 1,300 lb.
Grease produced per day (lb) = meals or customers per day × a grease factor in pounds per meal (table below).
Days to the 25% mark = step 1 ÷ step 2.
Suggested interval = the longest common schedule (weekly, every 2 weeks, monthly, every 6 weeks, every 2 months, or every 3 months) that doesn't exceed step 3, never longer than 90 days. If the estimate is under a week, it rounds down to whole days.

The formula and the gallons-to-pounds conversion follow the City of Independence, Missouri's Grease Interceptor Clean-Out Frequency Worksheet. The grease factors come from Appendix D of the Hampton Roads (Virginia) Regional Technical Standards for Grease Control Devices. They're rough estimates used for planning in those programs, not official Mississippi figures and not measurements of your kitchen.

Grease factors used (lb of grease per meal, rough estimates)

Kitchen type	No fryer, disposables	No fryer, washable dishes	Fryer, disposables	Fryer, washable dishes
Fast food / quick service, cooked on site (fryer-heavy) Hampton Roads: Fast Food - Full Prep row	0.025	0.0325	0.035	0.0455
Full-service restaurant (family, Italian, bar & grill) Hampton Roads: Family Restaurant, Italian, Bar and Grille rows	0.025	0.0325	0.035	0.0455
High-grease menu (seafood, steak house, BBQ, fried chicken, Chinese, Mexican) Independence: "Very High" row; Hampton Roads: Chinese, Mexican rows	0.035	0.0455	0.058	0.075
Buffet (including casino buffets) Hampton Roads: Buffet row	0.025	0.0325	0.035	0.0455
Bakery or donut shop Hampton Roads: Bakery, Donut Shop rows	0.025	0.0325	0.035	0.0455
Café, coffee shop, deli, or sandwich shop Hampton Roads: Coffee Shop, Deli, Sandwich Shop rows	0.005	0.0065	0.025	0.0325
Cafeteria or institutional kitchen, cooked on site (school, hospital, workplace) Hampton Roads: Cafeteria - Full Serve row	0.025	0.0325	0.035	0.0455
Cafeteria or institutional kitchen, heat-and-serve only Hampton Roads: Cafeteria - Heat & Serve row	0.005	0.0065	0.025	0.0325
Bar (drinks and light snacks) Hampton Roads: Bar - Drinks Only row	0.005	0.0065	0.025	0.0325

Each kitchen type maps to the closest menu types in the source tables, shown under each name. The two programs don't always agree: Independence's worksheet rates seafood, steak houses, barbecue, and fried chicken as "very high" grease producers, while the Hampton Roads table puts them with family restaurants. Because seafood and fried food are so common on the Coast, the calculator uses the higher figures for those menus.

What the estimate can't see

Your actual menu and cooking methods, and how much grease goes to the fryer-oil recycling bin instead of the drain
Kitchen habits like scraping plates into the trash, which the U.S. EPA notes can reduce how often devices need service
Food solids, garbage disposals, and the trap's real design and condition
Busy seasons, holiday weekends, and events on the Coast that push volume up

The 90-day reference in Harrison County

If your kitchen is in Biloxi, Gulfport, D'Iberville, Long Beach, or Pass Christian, the Harrison County Utility Authority (HCUA) regulation requires cleaning at whatever interval is necessary, and a generator that goes any 90-day period without cleaning, without an approved exception, can be ordered to have its trap inspected and tested. HCUA's permit checklist says to clean at least every 90 days. That makes 90 days a ceiling, not a target, which is why the calculator never suggests more than 90 days. Read more in our guides to HCUA grease trap fines and inspections and HCUA grease trap requirements.

In Bay St. Louis and the rest of Hancock County, the Hancock County Utility Authority's FOG ordinance sets a 30-day baseline for grease interceptors unless an exception is granted. In Ocean Springs, Pascagoula, and Jackson County, check with your city and the Jackson County Utility Authority. See how often to pump a grease trap in Biloxi and Gulfport for details.

Turning the estimate into a real schedule

Start with the suggested interval, or shorter if you're unsure.
Ask your provider to measure and record grease and solids depth at every pump-out.
If the trap is near or past 25% at pump-out, shorten the interval. If it's well under, ask whether it can be extended, without passing your local maximum.
Watch for signs your trap needs pumping sooner, like slow drains and odors.

Want a provider to confirm your interval?

Request free quotes from local grease trap providers. They can measure your trap and set a schedule that fits your kitchen.

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Grease trap calculator FAQ

How accurate is this grease trap calculator?

It gives a ballpark, not a measurement. Real grease output depends on your menu, cooking methods, how well staff scrape plates and keep fryer oil out of drains, whether solids or a garbage disposal feed the trap, and the trap's actual design. Use the result as a starting point, then have a licensed, permitted hauler measure grease and solids depth at each pump-out and adjust the interval from those readings.

What is the 25% rule?

The 25% rule is a widely used industry guideline: pump a grease trap or interceptor before floating grease plus settled solids take up about 25% of its liquid depth. Past that point, the trap has less calm water to separate grease, and more of it can pass into the sewer. Locally, the Hancock County Utility Authority's FOG ordinance uses the same 25% wetted-height trigger.

Is 90 days the legal maximum in Biloxi and Gulfport?

Biloxi, Gulfport, D'Iberville, Long Beach, and Pass Christian are in the Harrison County Utility Authority (HCUA) grease trap program. HCUA requires cleaning as often as needed; if a trap goes any 90-day period without cleaning and the generator has no approved exception, HCUA can order an inspection and testing, and its permit checklist says to clean at least every 90 days. Hancock County (Bay St. Louis) sets a 30-day baseline for interceptors. Confirm what applies to your permit with your sewer authority.

Where do the grease-per-meal numbers come from?

They are rough planning factors published by municipal grease (FOG) programs for sizing interceptors and setting pump-out frequency: the City of Independence, Missouri's clean-out frequency worksheet and the Hampton Roads, Virginia regional grease control standards. They are not Mississippi figures and not measurements of your kitchen.

How do I find my grease trap size?

Check an old pump-out manifest or service record (it often lists gallons), your building's plumbing plans, or the label on an indoor unit. If you still don't know, choose "Not sure" on our quote form and a provider can locate and measure it on the first visit.

Can enzymes or additives let me pump less often?

Don't count on it. Products sold to "dissolve" grease can push it further down the line, where it hardens in the sewer. Hancock County's ordinance prohibits surfactants, solvents, and emulsifiers, including enzymes and soap, in grease interceptors. Ask your provider before adding anything to a trap.

Sources

General information, not legal advice. Published October 27, 2026 · Last reviewed October 27, 2026. Rules and fees change, so confirm with your sewer authority.

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Disclosure: Biloxi Grease Trap is a referral service, not a pumping company. Independent providers quote and perform all work and may compensate us for referrals.

Grease Trap Pumping Calculator (Biloxi & Gulfport, MS)