How Many Porta Potties Do I Need? Calculator and Charts
Enter your guest count and hours to get a unit count, the accessible unit, and handwashing stations, with every step shown.
Reviewed by Tyson, owner · Updated
How many porta potties do you need for an event?
You need 1 porta potty per 50 guests for an event up to 4 hours, 1 per 40 guests for 5 to 8 hours, and 1 per 35 guests beyond 8 hours. Add 1 unit for every 4 when alcohol is served. Make at least 5% of units, minimum 1, wheelchair-accessible.
Assumptions in the calculator
- Base rate: 50 / 40 / 35 guests per unit by event length (Tyson's sizing method, the same one we use on every booking call).
- Alcohol: +1 unit for every 4 units, minimum +1.
- Accessible units: 5% per cluster, minimum 1, from the 2010 ADA Standards, section 213.2.
- Handwashing: 1 two-sided station per 2 toilets when food is served.
Porta potty chart by guest count and event length
For 100 guests at a 4-hour event you need 2 porta potties; for 6 hours, 3; with alcohol, 4. For 250 guests you need 5 units for 4 hours and 7 for 6 hours. Counts below already include 1 wheelchair-accessible unit per cluster.
| Guests | ≤4 hrs | 5–8 hrs | >8 hrs | 5–8 hrs + alcohol |
|---|---|---|---|---|
| 25 | 1 | 1 | 1 | 2 |
| 50 | 1 | 2 | 2 | 3 |
| 75 | 2 | 2 | 3 | 3 |
| 100 | 2 | 3 | 3 | 4 |
| 150 | 3 | 4 | 5 | 5 |
| 200 | 4 | 5 | 6 | 6 |
| 300 | 6 | 8 | 9 | 10 |
| 500 | 10 | 13 | 15 | 16 |
| 1,000 | 20 | 25 | 29 | 31 |
Worked example
A 150-guest wedding reception lasting 6 hours with a bar: 150 ÷ 40 = 3.75, rounded up to 4 units. Alcohol adds 1 unit, for 5. One of the 5 is wheelchair-accessible. Food is served, so add 3 handwashing stations (5 ÷ 2 = 2.5, rounded up).
How many porta potties does a construction site need?
OSHA requires at least 1 toilet for up to 20 workers and 1 seat plus 1 urinal per 40 workers above that, under 29 CFR 1926.51 Table D-1. For a 40-hour week with weekly service, we recommend 1 standard unit per 10 workers so units stay usable until service day.
| Crew | OSHA minimum | Recommended |
|---|---|---|
| 1–10 | 1 | 1 |
| 11–20 | 1 | 2 |
| 21–40 | 1 seat + 1 urinal | 3–4 |
| 41–80 | 2 seats + 2 urinals | 5–8 |
When should you add more units than the chart shows?
Add 1 more unit than the chart when most guests are women or children, when everyone breaks at the same time (ceremonies, races, intermissions), when it is hot, or when the house bathroom is closed to guests. Short lines matter more than the exact count.
- Races and festivals: everyone uses the restroom before the start; plan 1 unit per 30–40 runners near the start line.
- Kids' parties: add 1 unit and a handwashing station.
- Waterfront parties in July and August: heat speeds up odor; add a service visit on multi-day events.