Uses our planning method: 1 unit per 50 guests up to 4 hours, 1 per 40 up to 8 hours, 1 per 30 beyond, plus 1 unit for every 5 when alcohol is served and 1 hand-wash station per 5 units.
The 5-step sizing method for events
This is our planning method, based on industry sizing charts. Divide guests by 50 for events up to 4 hours, by 40 for events up to 8 hours, and by 30 for all-day events. Then add units for alcohol, hand-wash stations for the total, and make at least 1 unit wheelchair-accessible. Always round up.
- Base count by length: up to 4 hours, guests ÷ 50. Over 4 and up to 8 hours, guests ÷ 40. Over 8 hours, guests ÷ 30. Round up.
- Alcohol: if beer, wine or a bar is served, add the base count ÷ 5, rounded up.
- Hand washing: add 1 hand-wash station for every 5 units in the total, rounded up. Serve food? Plan at least 1.
- Access: make at least 1 unit in each group a wheelchair-accessible unit. In large groups, make 5% accessible, rounded up.
- Trailers: each restroom trailer stall counts as 1 unit.
The wheelchair-accessible unit counts as one of your units. It does not add to the total.
How many porta potties do I need for 100 guests drinking beer?
A 100-guest party that runs 5 hours with beer needs 4 porta potties and 1 hand-wash station. One of the 4 units should be wheelchair-accessible. The party runs past 4 hours, so the base uses 1 unit per 40 guests. The beer adds 1 more unit to the count.
- Base: 5 hours is over 4, so 100 ÷ 40 = 2.5, rounded up to 3 units.
- Alcohol: 3 ÷ 5 = 0.6, rounded up to 1 more unit. Now 4 units.
- Hand washing: 4 ÷ 5 = 0.8, rounded up to 1 station.
- Access: 1 of the 4 is a wheelchair-accessible unit.
Planning a home party? Our backyard party porta potty guide covers placement and gates.
Example: 250-guest wedding lasting 6 hours
A 250-guest wedding that lasts 6 hours needs 7 porta potties without alcohol and 9 with an open bar. Plan 2 hand-wash stations either way. Make at least 1 unit wheelchair-accessible. Many couples cover part of the count with a restroom trailer. Each trailer stall counts as 1 unit.
- Base: 6 hours is over 4, so 250 ÷ 40 = 6.25, rounded up to 7 units.
- Alcohol: 7 ÷ 5 = 1.4, rounded up to 2. Now 9 units.
- Hand washing: 9 ÷ 5 = 1.8, rounded up to 2 stations.
- Access: 5% of 9 is 0.45, rounded up to 1 wheelchair-accessible unit.
- Trailer option: a 3-stall trailer plus 6 units, one of them wheelchair-accessible, also makes 9.
See wedding restroom rental options or compare restroom trailers before you decide.
Event chart: 50 to 500 guests
This event chart shows total units for 50 to 500 guests at 2, 4, 6 and 8 hours. The first number is the count without alcohol. The number in parentheses includes alcohol. Add 1 hand-wash station for every 5 units, and make at least 1 unit wheelchair-accessible.
| Guests | 2 hours | 4 hours | 6 hours | 8 hours |
|---|---|---|---|---|
| 50 | 1 (2) | 1 (2) | 2 (3) | 2 (3) |
| 100 | 2 (3) | 2 (3) | 3 (4) | 3 (4) |
| 150 | 3 (4) | 3 (4) | 4 (5) | 4 (5) |
| 200 | 4 (5) | 4 (5) | 5 (6) | 5 (6) |
| 250 | 5 (6) | 5 (6) | 7 (9) | 7 (9) |
| 300 | 6 (8) | 6 (8) | 8 (10) | 8 (10) |
| 400 | 8 (10) | 8 (10) | 10 (12) | 10 (12) |
| 500 | 10 (12) | 10 (12) | 13 (16) | 13 (16) |
The 2-hour and 4-hour columns match because both use 1 unit per 50 guests. The 6-hour and 8-hour columns match because both use 1 unit per 40 guests. All-day events over 8 hours use 1 per 30, so 200 guests for 10 hours need 7 units. For multi-day events, ask about mid-event service so units stay fresh.
Construction crews: OSHA minimum vs our recommendation
OSHA Table D-1 sets the legal minimum: 1 toilet for 20 or fewer workers. Larger crews need 1 toilet seat and 1 urinal per 40 workers, or per 50 at 200 or more. Our recommendation is 1 unit per 10 workers on a 40-hour week with weekly service. That keeps lines and odor down.
| Workers on site | OSHA Table D-1 legal minimum | Our recommendation (40-hour week, weekly service) |
|---|---|---|
| 5 | 1 toilet | 1 unit |
| 10 | 1 toilet | 1 unit |
| 15 | 1 toilet | 2 units |
| 20 | 1 toilet | 2 units |
| 25 | 1 toilet seat + 1 urinal | 3 units |
| 40 | 1 toilet seat + 1 urinal | 4 units |
| 60 | 2 toilet seats + 2 urinals | 6 units |
| 80 | 2 toilet seats + 2 urinals | 8 units |
| 100 | 3 toilet seats + 3 urinals | 10 units |
| 200 | 4 toilet seats + 4 urinals | 20 units |
Each PolyJohn PJN3 standard unit has a toilet seat and a urinal. Crews working 50 or 60 hours a week fill tanks faster, so add a unit or an extra service visit. OSHA rule 1926.51(f) calls for washing facilities wherever crews handle paint, coatings or other contaminants. Read our OSHA porta potty guide for Tennessee for the details.
Example: 12-person framing crew
A 12-person framing crew needs 1 toilet by OSHA rules, but we recommend 2 units with weekly service. Twelve workers divided by 10 is 1.2, which rounds up to 2. Two units keep lines short. They also keep tanks from overfilling between weekly visits, since 12 people fill one tank fast.
In Putnam County, set the unit before the first inspection. See construction porta potty rental for weekly service details.
Example: 30-person crew
A 30-person crew legally needs at least 1 toilet seat and 1 urinal under OSHA Table D-1. We recommend 3 units with weekly service, since 30 divided by 10 equals 3. OSHA 1926.51(f) calls for washing facilities when crews handle paint, coatings or other contaminants. We recommend a station on most crews.
Spread the 3 units across the site if the crew works far apart. A worker who walks 5 minutes each way loses time on every trip. Our hand-wash station rentals refill at each service visit.
When to add units beyond the chart
Add 1 unit beyond the chart when it is hot, when guests arrive all at once, or when the crowd is mostly women and children. Summer days in Cookeville average about 88°F. Heat makes lines feel longer. Units spread across a large site also need extra count so no one walks far.
- Food and drinks: heavy drinking of any kind fills tanks faster than the chart assumes.
- Breaks all at once: church services, school games and ceremonies send everyone at the same moment.
- Two drop points: a field with parking far from the tent needs units in both places.
- Farm crews: OSHA 1928.110 calls for 1 toilet and 1 hand-wash station per 20 field workers. See farm porta potty rental.
Questions about sizing
Count every child who uses a toilet as a guest, size for the busiest hours rather than total visitors, and keep at least one accessible unit in each cluster. A 3-stall trailer covers three units, food events need a hand-wash station per five toilets, and one unit handles a 40-person party without alcohol.
Do kids count as guests when sizing porta potties?
Count every child old enough to use a toilet as a full guest. Kids tend to use restrooms often and with little warning, so a party with many children can need one unit more than the chart. Babies in diapers can be left out of the count.
Can one restroom trailer replace several porta potties?
A restroom trailer can replace part of the unit count, because each trailer stall counts as 1 unit. A 3-stall trailer covers 3 units of the total. Keep at least 1 wheelchair-accessible unit beside the trailer, since trailers have steps, and count it as one of your units.
How many wheelchair-accessible units does a public event need?
The 2010 ADA Standards, section 213.2, say that in each cluster of portable toilets, at least 5% must be accessible and never fewer than 1. A cluster of 20 units needs 1 accessible unit. A cluster of 25 needs 2, because 5% of 25 is 1.25 and you round up.
What if guests come and go all day instead of staying the whole time?
Size for the busiest few hours, not the total visitors. A festival with 1,000 visitors over 8 hours may have only 300 people on site at the peak. Use that peak number in the calculator above, and set the hours to the full length of the event.
How many hand-wash stations do food vendors need?
Plan 1 hand-wash station for every 5 toilets, and add 1 close to the food area when vendors serve meals. Each 2-station unit holds about 22 gallons of water, good for nearly 350 uses per fill. Long events with heavy food traffic may need a refill visit.
Is one porta potty enough for a 40-person birthday party?
One standard porta potty covers 40 guests for up to 8 hours without alcohol. Add a second unit if the party serves beer or wine, or if it runs all day past 8 hours. Keeping the house bathroom open for older relatives also takes pressure off the single unit.