How many porta potties do I actually need?

Almost everyone who calls us asks this question, and almost everyone guesses low. Here is how to get it right the first time.

Start with the base ratio

For events: one unit per 50 guests for a four-hour event.

For job sites: OSHA 1926.51 requires one toilet for up to 20 workers, two for 21–199, and one more per additional 40 workers. In practice, plan one per 10 workers — the OSHA number is a legal minimum, not a comfort target.

Then apply the adjustments

The base ratio assumes a short, dry, evenly-mixed event. Real events are not that.

• Alcohol served: add 20–25% more units. People drink more and go more often.
• Event runs longer than 6 hours: add another 20%.
• Predominantly female attendance: add units. The standard ratio assumes a mix, and women's usage times run longer.
• Food service: does not change toilet count much, but it does mean you need hand-wash stations rather than sanitizer alone.
• Multi-day event: service frequency matters more than unit count. Daily service on fewer units usually beats more units serviced once.

Worked examples

200-guest wedding reception, 5 hours, bar open: 200 ÷ 50 = 4 base units. Add 25% for alcohol and 20% for duration → roughly 6 stations. That is typically a 3-station restroom trailer plus a standalone ADA unit, or 6 standard units at a more casual venue.

30-person construction crew, 6-month job: OSHA minimum is 2. Practical count is 3 standard units plus a hand-wash station, on weekly service. If the crew scales to 50 during framing, go to 5.

1,000-person festival, 8 hours, beer garden: 1,000 ÷ 50 = 20 base units. Add 25% for alcohol and 20% for duration → about 29 units, distributed across at least three locations, with at least 2 ADA units and daily service.

The two mistakes that actually cause problems

Clustering everything in one spot. Twenty units in one row at the back of a venue creates a line at the near end and empty units at the far end. Distribute them.

Forgetting ADA. Public events are required to provide accessible restrooms. This is the most common oversight we see, and it surfaces the week of the event when there is no inventory left.

Still not sure?

Call us with your headcount, how long the event runs, and whether alcohol is involved. We size these every day and we would rather talk it through than have you guess.