Guide

How many porta potties do I need?

For most events, plan on about 1 standard unit for every 50 guests over 4 hours, then add more for longer events or when alcohol is served. Jobsites follow a different rule, set by OSHA. This guide covers both, plus accessible units, hand wash stations and where to put everything.

By the pottyfind team. Updated October 5, 2026. General guidance only; check the rules where you live.

The quick rule for events

Rental companies and event planners use a simple starting point: 1 standard unit for every 50 guests for an event of up to 4 hours. Longer events need more, because the same guests keep coming back. Our calculator adds about an eighth more for each extra hour, and a fifth more when alcohol is served.

Here is what that rule gives without alcohol. It is a planning rule of thumb, not a law, and a rental company that knows your venue may suggest more.

If alcohol is served, multiply by 1.2 and round up. A 6 hour wedding for 150 guests with a bar works out to 5 units, for example. The porta potty calculator does this math for any guest count and adds the accessible units and hand wash stations for you.

What changes the count

• Length of the event. A 2 hour ceremony and an all-day festival with the same crowd need very different numbers.
• Drinks. Beer, wine and soft drinks all raise the count. Hot days with lots of water do too.
• Rush times. Halftime, intermissions and the end of a ceremony send everyone at once. If lines matter, add units rather than relying on the average.
• Who is coming. Events where most guests are women tend to need more toilets, since a standard unit's urinal goes largely unused.
• Multi-day events. Units fill up. Plan for service each day, or more units, or both.
• Comfort. For weddings and formal events, deluxe flushing units or a restroom trailer may suit the setting better than standard units.

ADA accessible units

Under the 2010 ADA Standards for Accessible Design (section 213.2), where portable toilets are grouped together, at least 5 percent of the units in each group must be accessible, and that rounds up to at least one per group. Accessible units must be marked with the International Symbol of Accessibility.

An accessible unit has a level entry, more room inside to turn a wheelchair, and grab bars. Put it on firm, level ground along a path a wheelchair can use, not on soft grass or gravel at the far edge of the field.

The ADA covers businesses, governments and events open to the public. A party at your own home is usually not covered, but an accessible unit is still the right call if any guest uses a wheelchair or walker, and many guests simply like the extra room.

Jobsites: the OSHA rule

For construction, the federal minimum comes from OSHA rule 29 CFR 1926.51(c). It counts toilet seats and urinals by the number of workers:

A standard portable unit has a seat and a urinal, so one unit covers one "seat and urinal" in the table. A crew of 60 needs at least 2 units, for example. The rule does not apply to mobile crews that have transportation readily available to nearby toilets.

OSHA sets a minimum. Units that are only cleaned once a week fill up fast at the minimum, so many contractors plan on about 1 unit per 10 workers. Some states and project contracts add their own requirements, so check yours.

Hand wash stations

On construction sites, OSHA requires washing facilities. Under 29 CFR 1926.51(f)(3), lavatories must be made available at all places of employment, with running water, hand soap and towels or air dryers. The rule does not apply to mobile crews, or to work locations that are normally unattended, when the workers there have transportation readily available to nearby washing facilities. Washing facilities must also be near the work when crews apply paints, coatings, herbicides or insecticides (1926.51(f)(1)).

At events, hand washing matters most near food. Local health departments often set their own rules for events that serve food, so ask them early. A common planning ratio, and the one our calculator uses, is 1 hand wash station for every 4 units. Deluxe units with a built-in sink count toward that, and hand sanitizer is a good extra but not a substitute where soap and water are required.

Where to put them

• Level, firm ground. A unit on a slope can tip, and doors on a tilted unit may not close well.
• A spot the service truck can reach. The pump truck parks nearby and runs a hose to each unit, so ask the company how close it needs to get.
• Away from food, and downwind of where people eat, but close enough that guests do not wander far.
• Light for evening events. A dark path to the restrooms is a safety problem.
• Spread out on big sites. Two or three groups near where people gather beat one long row at the far end.
• Secured in wind. On open fields and high jobsites, ask about stakes or tie-downs.

How often units need service

Construction and long-term rentals usually include one service a week: pumping, cleaning and restocking paper. If units fill up before then, add a second weekly service or more units. For events, a one-day rental is usually delivered before and picked up after. Events that run more than one day often need service every day.

When you compare quotes, ask what the price includes: delivery and pickup, how many services, hand sanitizer, and any damage waiver or fuel fee.

Sources

• OSHA, 29 CFR 1926.51, Sanitation (construction)
• 2010 ADA Standards for Accessible Design, section 213.2