Porta potty calculator
How the calculator works: it finds the PSAI row at or above your guest count and the column at or above your hours. If alcohol is served or it will be 80°F or hotter, it adds 1 unit for every 4 (PSAI suggests 20–30% more). It sets at least 5% of units as wheelchair-accessible, with a minimum of 1, and 1 hand wash station per 10 toilets. The construction tab uses OSHA Table D-1.
How many porta potties do I need for an event?
An event needs 1 porta potty for up to 50 guests over 4 hours, 2 for 100 guests, and 7 for 500 guests over 6 hours, according to the Portable Sanitation Association International chart. The chart assumes each guest visits once every 4 hours and that units are not pumped during the event.
| Guests | 1 hr | 2 hr | 4 hr | 6 hr | 8 hr | 10 hr |
|---|---|---|---|---|---|---|
| Up to 50 | 1 | 1 | 1 | 2 | 2 | 2 |
| 100 | 2 | 2 | 2 | 3 | 3 | 3 |
| 250 | 2 | 2 | 2 | 3 | 3 | 3 |
| 500 | 2 | 4 | 5 | 7 | 9 | 12 |
| 1,000 | 4 | 6 | 8 | 9 | 12 | 13 |
| 2,000 | 5 | 6 | 12 | 16 | 20 | 25 |
| 5,000 | 12 | 15 | 25 | 38 | 50 | 63 |
| 10,000 | 15 | 25 | 50 | 75* | 100 | 125 |
| 20,000 | 25 | 50 | 100 | 150 | 200 | 250 |
Source: PSAI Standards for Special Events. PSAI also publishes ANSI Z4.3 for job sites (PSAI standards).
Worked example: a 150-guest wedding with a bar
A 150-guest, 5-hour wedding with a bar needs 4 porta potties. Start with the PSAI chart: 150 guests rounds up to the 250 row, and 5 hours rounds up to the 6-hour column, which gives 3 units. Add 1 unit because alcohol is served. Make 1 of the 4 wheelchair-accessible and add 1 hand wash station.
- Chart row: 150 guests → use the 250 row.
- Chart column: 5 hours → use the 6-hour column. Result: 3 units.
- Alcohol: add 1 for every 4 units, rounded up → +1 = 4 units.
- Accessible: 5% of 4 is 0.2 → round up to 1 accessible unit.
- Hand wash: 4 toilets is under 10 → 1 station.
What does Irving require for permitted events?
Irving requires minimum toilet counts for every permitted special event under city code §33B-14. A 101–250 person event needs 3 units for 4 hours and 6 for 8 hours. A 501–1,000 person event needs 8 for 4 hours. Add 1 hand wash station within 20 feet for every 4 toilets.
| Daily attendance | 1 hour | 4 hours | 8 hours | 10 hours |
|---|---|---|---|---|
| Up to 50 | 1 | 1 | 2 | 2 |
| 101–250 | 2 | 3 | 6 | 8 |
| 251–500 | 3 | 5 | 7 | 8 |
| 501–1,000 | 5 | 8 | 10 | 12 |
| 1,001–2,000 | 8 | 17 | 19 | 20 |
Irving's coordinator can require more units when attendance passes 10,000, the event runs over 10 hours a day, alcohol is served, or past events showed a need (§33B-14(b)). Source: Irving Code Chapter 33B. When Irving's minimum and the PSAI chart differ, use the higher number.
How many porta potties does a construction crew need?
A construction crew of 20 or fewer workers needs at least 1 porta potty under OSHA 29 CFR 1926.51. Crews of 20 to 199 need 1 toilet seat and 1 urinal per 40 workers, and crews of 200 or more need 1 of each per 50. Our standard unit has a seat and a urinal.
| Workers on site | OSHA minimum (29 CFR 1926.51 Table D-1) | Example |
|---|---|---|
| 20 or fewer | 1 toilet | A 6-person roofing crew needs 1 unit |
| 20 to 199 | 1 toilet seat and 1 urinal per 40 workers | 85 workers ÷ 40 = 2.1, round up to 3 units |
| 200 or more | 1 toilet seat and 1 urinal per 50 workers | 260 workers ÷ 50 = 5.2, round up to 6 units |
Worked example: 85 workers ÷ 40 = 2.125 → round up to 3 units (legal minimum). For 10-hour days, we recommend 1 more unit or a second weekly service. Source: 29 CFR 1926.51. Farms with 11 or more field workers follow OSHA 1928.110: 1 toilet and 1 hand wash station per 20 workers within a quarter-mile walk.
How many wheelchair-accessible units do I need?
You need at least 5% of portable units in each cluster to be wheelchair-accessible under 2010 ADA Standards section 213.2, which means at least 1 per cluster. A cluster of 20 needs 1; a cluster of 21 to 40 needs 2. Place each on a firm, level route.
Source: U.S. Access Board guide. Confirm requirements with your venue or permit office; this is not legal advice.
Sizing questions
Do I count guests or peak attendance?
Count peak attendance — the most people on site at one time. For all-day events with turnover, count the busiest 4 hours.
Do kids count as guests?
Yes. Children use restrooms often. Count them in the total.
What if the venue has indoor restrooms?
Subtract their capacity only if guests can reach them easily. Many hosts still add 1–2 units near the party.
Do I need more units for a long event?
Yes, or a mid-event service. A pump-and-restock visit resets each unit's capacity.
Is the calculator legal advice?
No. It is a planning tool based on public charts. Your permit office or venue has the final say.