How Many Porta Potties Do I Need?
For an event, start at one unit per 50 guests for four hours and add from there. For a job site the number is not advice, it is federal law: 29 CFR 1926.51(c). Both tables are below, and the calculator uses nothing else.
Event ratios, from ANSI/PSAI Z4.3
| Guests | 4 hours | 6 hours | 8 hours |
|---|---|---|---|
| 50 | 1 | 2 | 2 |
| 100 | 2 | 3 | 3 |
| 250 | 5 | 6 | 7 |
| 500 | 10 | 12 | 13 |
| 1,000 | 20 | 23 | 25 |
| 2,500 | 50 | 56 | 63 |
Add roughly 15–20% where alcohol is served — people drink more and stay longer. Add one hand-wash station per four units where food is served.
Job sites, from 29 CFR 1926.51(c)(1)
| Workers on site | Minimum required |
|---|---|
| 20 or fewer | 1 toilet |
| More than 20 | 1 toilet seat and 1 urinal per 40 workers |
| More than 200 | 1 toilet seat and 1 urinal per 50 workers |
These are minimums, not targets. A crew that loses ten minutes each way walking to a single unit costs more in time than the second unit costs to rent.
ADA units
Any event open to the public should have at least one wheelchair-accessible unit, and the common industry guidance is 5% of the total with a minimum of one. They are also the first thing to run out on a busy weekend, so book that one before the rest. 1100 of the 1,977 companies our team checked say they rent them.