Porta potty calculator
How it calculates: it picks the PSAI row at or above your guest count and the column at or above your hours. If drinks are served or it will be 80°F or hotter, it adds 1 unit for every 4 (PSAI suggests 20–30% more). It makes at least 5% of the units wheelchair-accessible, minimum 1, and adds 1 hand wash station per 10 toilets. The crew tab uses OSHA Table D-1.
How many porta potties does an event need?
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 uses a restroom once every 4 hours and that no units are 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 |
Quick visual guides
- Sizing porta potties for a Killeen event (web story)
Source: PSAI Standards for Special Events. PSAI also maintains the ANSI Z4.3 standard for job sites (PSAI standards).
Worked example: a 200-guest Fort Hood retirement party
A 200-guest, 5-hour retirement party with a bar needs 4 porta potties. The PSAI chart puts 200 guests in the 250 row and 5 hours in the 6-hour column, which gives 3 units. Add 1 unit because drinks are served. Make 1 of the 4 wheelchair-accessible and add 1 hand wash station.
- Row: 200 guests → the 250 row.
- Column: 5 hours → the 6-hour column. Result: 3 units.
- Drinks: 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 washing: under 10 toilets → 1 station.
What does Killeen require for permitted events?
Killeen requires a special event permit sorted into four tiers by attendance: Tier 1 up to 100 people, 21 days ahead; Tier 2 up to 500, 30 days; Tier 3 up to 1,000, 60 days; and Tier 4 over 1,000, 90 days. The permit page does not set a toilet count, so organizers use the PSAI chart.
| Tier | Expected attendance | Apply at least | Street use | Insurance (per person / per occurrence) |
|---|---|---|---|---|
| Tier 1 | Up to 100 (block parties) | 21 days ahead | Limited residential closures | Not listed |
| Tier 2 | 101–500 | 30 days ahead | No road closures | $300,000 / $500,000 |
| Tier 3 | 501–1,000 | 60 days ahead | Lots, roads or intersections may close | $1M / $2M |
| Tier 4 | Over 1,000 | 90 days ahead | Lots, roads or intersections may close | $1M / $5M |
Source: Killeen Special Event Permitting Process. Nearby cities ask for restrooms on the site plan: Harker Heights, Nolanville, Gatesville and College Station all do. Check your city page from our service areas.
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 21 to 199 need 1 seat and 1 urinal per 40 workers, and crews of 200 or more need 1 of each per 50. Every standard unit we rent has both a seat and a urinal.
| Crew size | OSHA floor (29 CFR 1926.51, Table D-1) | Worked example |
|---|---|---|
| 1–20 workers | 1 toilet | A 5-person framing crew in Killeen: 1 unit |
| 21–199 workers | 1 seat plus 1 urinal for every 40 workers | 120 workers ÷ 40 = 3 units |
| 200 or more | 1 seat plus 1 urinal for every 50 workers | 230 workers ÷ 50 = 4.6, so 5 units |
Worked example: 95 workers ÷ 40 = 2.4, rounded up to 3 units as the legal minimum. On 10-hour days we suggest one more unit or a second weekly cleaning.
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. Cedar Park also requires one unit per four houses on home builds.
How many wheelchair-accessible units are required?
At least 5% of the portable units in each group must be wheelchair-accessible under section 213.2 of the 2010 ADA Standards, which means at least 1 per group. A group of 20 needs 1 accessible unit, and a group of 21 to 40 needs 2. Each one needs 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
Should I count all guests or the peak crowd?
Count the peak — the most people there at one time. For all-day events, use the busiest 4 hours.
Do children count?
Yes. Kids use restrooms often, so include them.
What if the venue has indoor restrooms?
Subtract them only if guests can reach them easily. Many hosts still add 1–2 units near the party.
Do long events need more units?
Yes, or a mid-event cleaning. A pump-and-restock visit resets each unit.
Is the calculator legal advice?
No. It is a planning tool based on public charts. Your permit office or venue decides.