What is the method for sizing porta potties?
Start with 1 standard unit per 50 guests for an event up to 4 hours, rounded up. Add 1 unit per 100 guests if the event runs longer than 4 hours. Add 1 more unit per 100 guests if alcohol is served. Then add accessible units and 1 hand wash sink for every 4 toilets.
- Base units: guests ÷ 50, rounded up.
- Long event: over 4 hours, add guests ÷ 100, rounded up.
- Alcohol: if served, add guests ÷ 100, rounded up.
- Accessible: for public events, add at least 1 wheelchair-accessible unit per cluster (ADA 213.2: 5%, minimum 1).
- Handwashing: 1 two-station sink for every 4 toilets, rounded up, unless you pick deluxe units with built-in sinks.
We reviewed 185 recorded calls from people renting porta potties in 2026 (172 reached a live conversation). Callers had heard 3 different rules (1 per 40, 50 or 100 guests). We use one published method.
Porta potty calculator
Method: 1 standard unit per 50 guests for up to 4 hours; add 1 per 100 guests past 4 hours; add 1 per 100 guests with alcohol; accessible units per 2010 ADA Standards 213.2; 1 two-station sink per 4 toilets.
Quick chart: how many porta potties for 25 to 500 guests?
For an event of 4 hours or less without alcohol, 25 to 50 guests need 1 unit, 100 guests need 2, 200 need 4 and 500 need 10. A 500-guest event that runs over 4 hours with alcohol needs 20 units. Use the chart, then add accessible units and sinks.
| Guests | Up to 4 hrs, no alcohol | Up to 4 hrs, with alcohol | Over 4 hrs, no alcohol | Over 4 hrs, with alcohol | Sinks for the last column |
|---|---|---|---|---|---|
| 25 | 1 | 2 | 2 | 3 | 1 |
| 50 | 1 | 2 | 2 | 3 | 1 |
| 100 | 2 | 3 | 3 | 4 | 1 |
| 150 | 3 | 5 | 5 | 7 | 2 |
| 200 | 4 | 6 | 6 | 8 | 2 |
| 300 | 6 | 9 | 9 | 12 | 3 |
| 500 | 10 | 15 | 15 | 20 | 5 |
Counts are standard units only. For public events, add at least 1 wheelchair-accessible unit per cluster. Sinks follow the 1-per-4 rule and drop to zero if you choose deluxe units with built-in sinks.
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Call (972) 812-6200Get quoteWorked examples: birthday, wedding and church picnic
A 3-hour backyard birthday for 40 guests needs 1 unit. A 6-hour, 150-guest wedding with a bar needs 7 units, at least 1 accessible, plus 2 sinks. A 4-hour church picnic for 120 guests needs 3 standard units plus 1 wheelchair-accessible unit. Each example follows the same 5 steps.
Backyard birthday: 40 guests, 3 hours, no alcohol
40 ÷ 50 = 0.8, round up to 1. Under 4 hours, no alcohol, private home. Total: 1 standard unit. See our party and weekend guide.
Wedding: 150 guests, 6 hours, open bar
150 ÷ 50 = 3. Over 4 hours: 150 ÷ 100 = 1.5, round up to 2. Alcohol: 150 ÷ 100 = 1.5, round up to 2. 3 + 2 + 2 = 7. Total: 7 units, at least 1 of them accessible, plus 2 hand wash stations (7 ÷ 4 = 1.75, round up to 2). See our wedding restroom guide.
Church picnic: 120 guests, 4 hours, no alcohol
120 ÷ 50 = 2.4, round up to 3. Exactly 4 hours does not trigger the long-event add. No alcohol. It is open to the public, so add 1 wheelchair-accessible unit. Total: 3 standard units plus 1 accessible unit, plus 1 hand wash station (3 ÷ 4, round up to 1).
How many porta potties does a jobsite need?
Jobsites follow OSHA Table D-1, not the event method. Twenty or fewer workers need 1 toilet. Over 20 workers need 1 toilet seat and 1 urinal per 40 workers. A crew of 45 needs 2 seats and 2 urinals, which is 2 standard units, since each PolyJohn PJN3 has a seat and a urinal.
The rule is OSHA 29 CFR 1926.51(c), Table D-1. Over 200 workers, it changes to 1 seat and 1 urinal per 50 workers. Handwashing is covered in 1926.51(f).
| Workers | OSHA minimum | Standard PJN3 units |
|---|---|---|
| 1 to 20 | 1 toilet | 1 |
| 21 to 40 | 1 seat + 1 urinal | 1 |
| 45 | 2 seats + 2 urinals (45 ÷ 40 = 1.125, round up to 2) | 2 |
| 100 | 3 seats + 3 urinals | 3 |
More on crews, weekly service and OSHA rules on our jobsite toilet guide.
How many wheelchair-accessible units do you need?
For public events, ADA 213.2 says at least 5% of portable toilets in each cluster must be accessible, and never fewer than 1. A cluster of up to 20 units needs 1 accessible unit; 21 to 40 units need 2. The ADA standard also calls for a 60-inch turning space, so confirm with your venue.
Read the rule at the U.S. Access Board, 2010 ADA Standards section 213. Count each cluster on its own. Two banks of 10 units need 1 accessible unit each, not 1 for the event.
Our accessible unit is a PolyJohn Comfort XL, 62 by 62 inches outside with a 32-inch door. For a private backyard party, it is your call, but a guest with a walker or wheelchair will need one.
How many hand wash stations do you need?
Plan 1 two-station hand wash sink for every 4 toilets, rounded up. Each PolyJohn Bravo sink holds 22 gallons of fresh water and gives about 350 uses per fill. Deluxe units carry their own sink with a 20-gallon tank rated for about 400 uses, so they need no separate station.
Standard units come with a hand sanitizer dispenser. Sinks with soap and paper towels are better near food, at weddings and anywhere kids are eating.
In our call study, 12% of callers (20 of 172) asked about handwashing. See our hand wash station details for specs.
Can a deluxe flushing unit serve as many guests as a standard unit?
Not quite. Plan about 50 guests per deluxe unit; that is our office guidance. Its 20-gallon sink tank covers about 400 hand washes, per the manufacturer. For bigger crowds, pair deluxe units with standard units. Both units have the same 60-gallon holding tank.
A common setup for a 150-guest wedding: deluxe units near the reception for guests who want a flush and sink, and standard units near parking or the bar for volume.
Check the tank details on the PolyJohn Fleet product page.
When should you add a mid-event service?
Add a mid-event service when an event runs 2 or more days, when daily crowds are near the top of the chart, or when deluxe units serve more than about 50 guests each. Service means pump out, clean, restock paper and sanitizer, and refill sinks. Long-term rentals get weekly service.
Extra service visits are available Monday through Saturday, quoted before they are scheduled.
Planning a crowd of 500 or more? Our large-event guide covers banks, service between festival days and lighting.