Sizing calculator
How Many Porta Potties Do I Need?
Plan 1 standard porta potty for every 250 guest-hours, round up, and add 1 for every 4 units when alcohol is served. Make at least 1 unit wheelchair-accessible. Construction crews follow OSHA: 1 unit per 40 workers.
By Dominic, owner · Reviewed
How many porta potties do I need for my event?
Most events need 1 standard porta potty for every 250 guest-hours. Multiply guests by hours, divide by 250 and round up. A 150-guest, 5-hour event needs 3 units; add 1 if alcohol is served, for 4. Make at least 1 unit wheelchair-accessible, and add 1 hand-washing station per 4 units.
How does the porta potty sizing method work?
The porta potty sizing method uses 3 whole-number steps. Step 1: guests × hours ÷ 250, rounded up. Step 2: when alcohol is served, add 1 unit for every 4 units from step 1, rounded up. Step 3: make 5% of the total, and at least 1, wheelchair-accessible.
| Guests | 3 hours | 5 hours | 8 hours | 5 hours with alcohol |
|---|---|---|---|---|
| 25 | 1 | 1 | 1 | 2 |
| 50 | 1 | 1 | 2 | 2 |
| 75 | 1 | 2 | 3 | 3 |
| 100 | 2 | 2 | 4 | 3 |
| 150 | 2 | 3 | 5 | 4 |
| 200 | 3 | 4 | 7 | 5 |
| 300 | 4 | 6 | 10 | 8 |
Standard units from our planning chart: guests × hours ÷ 250, rounded up, minimum 1. Alcohol adds 1 unit for every 4 units, rounded up. Add hand-washing stations when food is served, and make at least 1 unit wheelchair-accessible for public events.
Worked example: a 200-guest, 6-hour wedding with a bar. Step 1: 200 × 6 = 1,200 ÷ 250 = 4.8, round up to 5. Step 2: alcohol adds 5 ÷ 4 = 1.25, round up to 2, for 7 units. Step 3: 5% of 7 is 0.35, so 1 accessible unit. Order 6 standard units, 1 accessible unit and 2 hand-washing stations.
The 250 guest-hours figure is our planning chart, built from the roughly 200-use rating of a standard unit with headroom for lines at peak times. The accessible count follows 2010 ADA Standards section 213.2.
How many porta potties does a construction crew need?
A construction crew of 20 or fewer workers needs 1 porta potty under OSHA 29 CFR 1926.51. A crew of 21 to 199 needs 1 seat and 1 urinal per 40 workers, which is 1 standard unit per 40. A crew of 200 or more needs 1 per 50. Switch the calculator to construction crew.
The full table and handwashing rules are in the OSHA jobsite toilet requirements guide.
When should I add more porta potties than the chart shows?
Add 1 more porta potty than the chart shows in 4 cases: most guests are women or children, the event has one big break when everyone goes at once, the units will not be serviced for more than a day, or the event runs over 8 hours. Lines form fastest at weddings right after dinner.
For multi-day festivals, plan a pump and restock each night. Ask for a mid-event service on the event rental page.
Questions people ask before booking
How many porta potties for 50 people?
50 guests for up to 5 hours need 1 standard unit. Add a second when alcohol is served or the event runs 6 hours or more.
How many porta potties for 200 people?
200 guests for 5 hours need 4 standard units, or 5 with alcohol. Make 1 wheelchair-accessible.
How many porta potties for 500 people?
500 guests for 5 hours need 10 units, or 13 with alcohol, including 1 accessible unit, plus 3 to 4 hand-washing stations.
Does a restroom trailer count as several units?
Each trailer stall counts as about 1.5 standard units because guests use it faster and lines move quicker. A 2-stall trailer covers about 3 units.
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