How Many Porta Potties Do I Need?
One standard porta potty serves about 50 guests at an event of up to 4 hours, or 40 guests for 5 to 8 hours. Add 1 unit for every 4 when alcohol is served, 1 hand wash station per 2 toilets with food, and make 5% of each cluster wheelchair-accessible. Construction sites follow OSHA Table D-1.
Porta potty calculator
Enter your guest count and event length, or switch to the jobsite tab and enter your crew size. The calculator applies the Alan Rental Works sizing method and the OSHA and ADA rules shown below, and it explains each step in plain words under the result.
How many porta potties for an event?
Divide guests by 50 for events up to 4 hours, or by 40 for 5 to 8 hours, and round up. A 200-guest, 6-hour party needs 200 ÷ 40 = 5 units. With alcohol, add 1 unit per 4, so 6 units. With food, add 1 hand wash station per 2 toilets, so 3 stations.
| Guests | Up to 4 hrs | 5–8 hrs | 5–8 hrs + alcohol | Hand wash (with food) |
|---|---|---|---|---|
| 25 | 1 | 1 | 2 | 1 |
| 50 | 1 | 2 | 3 | 2 |
| 75 | 2 | 2 | 3 | 2 |
| 100 | 2 | 3 | 4 | 2 |
| 150 | 3 | 4 | 5 | 3 |
| 200 | 4 | 5 | 6 | 3 |
| 250 | 5 | 7 | 8 | 4 |
| 300 | 6 | 8 | 10 | 5 |
| 400 | 8 | 10 | 12 | 6 |
| 500 | 10 | 13 | 16 | 8 |
Assumptions behind the chart
- Guests are on site for the full event; staggered arrivals need fewer.
- About half the guests are women; mostly-female events (showers, bridal parties) should add 1 unit per 4.
- Units are not serviced during the event. Multi-day events repeat the count per day with service between days.
- The alcohol step is a whole-unit add: if the table says 5, add 1 for a total of 6.
How many porta potties for a construction site?
OSHA 29 CFR 1926.51(c) Table D-1 sets the legal minimum: 1 toilet for 20 or fewer workers, 1 seat and 1 urinal per 40 workers for 20 or more, and 1 per 50 for 200 or more. With weekly service, plan 1 standard unit per 10 workers so the tank lasts the week.
| Workers | OSHA minimum | Recommended (weekly service) |
|---|---|---|
| 10 | 1 | 1 |
| 20 | 1 | 2 |
| 40 | 1 seat + 1 urinal | 4 |
| 80 | 2 + 2 | 8 |
| 200 | 4 + 4 (per 50) | 20, or 10 with twice-weekly |
Source: OSHA 29 CFR 1926.51. Legal minimum shown separately from our recommendation.
How many accessible units does an event need?
The 2010 ADA Standards, section 213.2, say at least 5 percent of portable toilets in each cluster must be accessible, and never fewer than 1. A cluster of 6 needs 1. A cluster of 25 needs 2. Private home parties are usually exempt, but one accessible unit helps guests with walkers.
Source: U.S. Access Board, 2010 ADA Standards §213.2. Confirm with your venue or permit office.
Farms and field crews
OSHA 29 CFR 1928.110 requires 1 toilet and 1 handwashing facility per 20 field workers, within a quarter-mile walk, when 11 or more employees work in the field. See the OSHA field sanitation standard.
Worked examples
Here are five common orders worked out step by step with the same method the calculator uses. Each example shows the base count, the whole-unit adds, the hand wash stations and the accessible count so you can check the math yourself.
| Event | Base | Adds | Final order |
|---|---|---|---|
| Backyard grad party, 60 guests, 5 hrs, food, no alcohol | 60 ÷ 40 = 2 | Food: 1 station | 2 standard + 1 hand wash |
| Wedding, 150 guests, 6 hrs, bar + dinner | 150 ÷ 40 = 4 | Bar +1 → 5; food: 3 stations | 2-stall trailer, or 5 deluxe + 3 stations + 1 accessible |
| Church picnic, 100 guests, 3 hrs, food, public | 100 ÷ 50 = 2 | Food: 1 station; public: 1 accessible | 1 standard + 1 accessible + 1 station |
| 5K race, 400 runners, 3 hrs | 400 ÷ 50 = 8 | Public: 1 accessible | 7 standard + 1 accessible, at the start |
| Framing crew of 14, 5 days/week | OSHA: 1 | Recommended 14 ÷ 10 = 2 | 2 standard, weekly service |
Sizing questions
Do I need more porta potties if most guests are women?
Plan 1 extra unit for every 4 at showers and mostly-female events, because each visit takes longer.
Do kids count as guests?
Count kids over 5 as full guests. Toddlers in diapers can be left out of the count.
What if guests come and go all day?
Use the peak number on site at one time, not the total who visit.
Is one porta potty enough for a 3-hour party of 30?
One standard unit covers 30 guests for 3 hours with room to spare.
How many porta potties for a 3-day festival?
Size each day by its peak crowd and book service between days, so each morning starts with empty tanks.
Where does this sizing method come from?
It is Alan Rental Works' own planning method, built around the tank capacity of our units, plus the OSHA and ADA rules linked on this page.
Want us to check your count?
Call with your head count and hours. We'll confirm the order on the phone.
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