Porta potty count: key facts
- Up to 4 hours: 1 standard unit per 50 guests.
- Up to 6 hours: 1 per 40. Up to 8 hours: 1 per 30.
- Alcohol served: add 1 unit for every 4.
- Accessible: at least 5% of units per cluster, minimum 1 (ADA §213.2).
- Construction: 1 toilet for up to 20 workers; 1 seat + 1 urinal per 40 above that (OSHA Table D-1).
How many porta potties do I need?
Plan 1 standard porta potty per 50 guests for an event up to 4 hours, 1 per 40 guests up to 6 hours, 1 per 30 up to 8 hours and 1 per 25 beyond that. Add 1 unit for every 4 when alcohol is served. Make at least 5% of units accessible where required, and add 1 handwash station per 4 toilets.
Porta potty calculator
Calculator assumptions: guests per unit = 50 (≤4 h), 40 (≤6 h), 30 (≤8 h), 25 (>8 h), rounded up. Alcohol adds 1 unit per 4 base units, rounded up. Accessible = 5% of total, at least 1 (2010 ADA Standards §213.2). Handwash = 1 two-station sink per 4 toilets. This is the Dennis Rental Works dispatch sizing table — a planning method, not a legal minimum.
Porta potty chart: guests vs event length
This chart shows the standard units Dennis Rental Works recommends before adding units for alcohol. For example, 200 guests at a 6-hour event need 5 standard units, and 300 guests at an 8-hour event need 10. Add 1 unit per 4 when alcohol is served, and at least 1 accessible unit for 100 or more guests.
| Guests | Up to 4 hours | Up to 6 hours | Up to 8 hours |
|---|---|---|---|
| 50 | 1 | 2 | 2 |
| 100 | 2 | 3 | 4 |
| 150 | 3 | 4 | 5 |
| 200 | 4 | 5 | 7 |
| 300 | 6 | 8 | 10 |
| 500 | 10 | 13 | 17 |
Worked example: a 150-guest wedding with a bar
A 150-guest, 5-hour wedding with a bar needs 5 standard units. Step 1: 150 guests at 1 per 40 (up to 6 hours) = 3.75, rounded up to 4. Step 2: alcohol adds 1 unit per 4, so add 1. Total 5. Step 3: 5% of 5 is 0.25, rounded up to 1 accessible unit.
- 150 ÷ 40 = 3.75 → 4 units
- Alcohol: 4 ÷ 4 = 1 → +1 unit (total 5)
- Accessible: 5% × 5 = 0.25 → 1 of the 5 is accessible
- Food: 5 ÷ 4 = 1.25 → 2 handwash stations if food is served
A two-stall restroom trailer can replace about 3–4 standard units. See wedding restroom setups.
How many porta potties does a construction crew need?
A construction crew of 20 or fewer workers needs 1 toilet under OSHA 29 CFR 1926.51(c). Crews of 20 or more need 1 toilet seat and 1 urinal per 40 workers, and 200 or more need 1 seat and 1 urinal per 50. In Frisco, residential builders also need 1 unit per 5 building sites within 200 feet walking distance.
Use the crew calculator in our construction rules guide.
When should I add more units than the chart says?
Add units when the event has a bar, a long reception, mostly female guests, kids, summer heat or a single break when everyone goes at once, such as a halftime or intermission. Add a mid-event service instead when the event runs over 8 hours. Fewer units are fine when guests are spread out over a long open house.
Questions renters ask us
How many porta potties do I need for 100 people?
For 100 guests at a 4-hour event, plan 2 standard porta potties. Add 1 unit if alcohol is served, for 3 total. For a 6-hour event, plan 3 units, or 4 with alcohol. Include 1 wheelchair-accessible unit when guests may need one.
How many restrooms do I need for a 150-guest wedding?
A 150-guest, 5-hour wedding with a bar needs 5 standard units in our sizing table: 4 for the guest count and length, plus 1 because alcohol is served. One should be wheelchair-accessible. A two-stall restroom trailer can replace 3–4 standard units for most weddings.
Is one restroom trailer enough for 80 guests?
Yes. One two-stall restroom trailer serves about 80 guests for a 4–5 hour event. Add a wheelchair-accessible portable unit if any guest may need one, because many trailers have steps. Bigger crowds or longer events need a larger trailer or added units.
Do I need a handicap porta potty at my event?
Where accessible restrooms are required, the 2010 ADA Standards section 213.2 calls for at least 5% of portable units in each cluster, and no fewer than one, to be accessible. Dennis Rental Works recommends at least 1 accessible unit for any event of 100 or more guests.
How many porta potties does my crew need under OSHA?
OSHA 29 CFR 1926.51(c) Table D-1 sets the minimum. 20 or fewer workers need 1 toilet. 20 or more workers need 1 toilet seat and 1 urinal per 40 workers. 200 or more need 1 seat and 1 urinal per 50. Check your contract and permit for stricter rules.
