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How Many Porta Potties Do I Need?
A calculator and two tables that turn a guest count or a crew size into a unit count, using the PSAI event chart, the ADA 5% rule and OSHA Table D-1, with the math shown so you can check it.
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- EventsGuests ÷ 100 × hours ÷ 4, × 1.25 with alcohol or heat, rounded up; 5% accessible; 1 hand wash per 10 units.
- JobsitesOSHA: 1 toilet to 20 workers; 1 seat + 1 urinal per 40 above that; per 50 above 200.
- WeddingsDeluxe units at 1 per 75 guests per 4 hours; a 2-station trailer covers 150 guests.
- Long eventsDouble the count past 6 hours, or add mid-event pumping at $35 per unit.
- Then price itCount first, then see the pricing guide or request a quote below.
How many porta potties do I need for an event?
Divide guests by 100 (standard units) or 75 (deluxe units), multiply by hours ÷ 4, multiply by 1.25 for alcohol or heat above 80°F, and round up once. Make at least 5% of the units accessible and add one hand wash station per 10 units. A 150-guest, 5-hour wedding with a bar needs 4 deluxe-rate units: 2 × 1.25 × 1.25 = 3.1, rounded up to 4, with 1 of the 4 accessible.
Sizing calculator
Method: Martin Rental Works sizing rule built on the PSAI special-events standard (one use per person per 4 hours, 50/50 gender mix, no pumping during the event), the 2010 ADA Standards §213.2 5% rule, and the PSAI hand-wash ratio of 1 station per 1–10 units. Sources are linked at the bottom of the page. Deluxe flushing units size at 1 per 75 guests because guests take longer.
What does the event sizing table look like?
The table below shows standard-unit counts (guests ÷ 100 × hours ÷ 4, rounded up) for common guest counts and event lengths, before the alcohol, accessible and hand-wash adds. Read across for your event length, multiply by 1.25 for alcohol or heat and round up, make 5% accessible, and add one hand wash station per 10 units. Mid-event pumping at $35 per unit lets long events use the 4-hour column.
| Guests | 2 hours | 4 hours | 6 hours | 8 hours | 10 hours |
|---|---|---|---|---|---|
| 50 | 1 | 1 | 1 | 1 | 2 |
| 100 | 1 | 1 | 2 | 2 | 3 |
| 150 | 1 | 2 | 3 | 3 | 4 |
| 250 | 2 | 3 | 4 | 5 | 7 |
| 500 | 3 | 5 | 8 | 10 | 13 |
| 1,000 | 5 | 10 | 15 | 20 | 25 |
| 2,500 | 13 | 25 | 38 | 50 | 63 |
| 5,000 | 25 | 50 | 75 | 100 | 125 |
Local permit minimums are lower than these numbers. The City of Bethlehem Special Event Application recommends two toilets per 500 attendees with 5% accessible, and Lehigh County Parks require one toilet per 50 to 100 people with at least one accessible. The minimum gets you a permit; the table gets you short lines.
How many toilets does a construction site need?
OSHA 29 CFR 1926.51(c) Table D-1 requires one toilet for 20 or fewer workers, one toilet seat plus one urinal per 40 workers from 21 to 199, and one seat plus one urinal per 50 workers at 200 or more. A PolyJohn PJN3 provides one seat and one urinal, so divide the crew by 40 (or 50) and round up. A 45-worker crew needs 2 units; a 130-worker crew needs 4.
| Workers | OSHA minimum (PJN3 units) | Our recommendation | Service |
|---|---|---|---|
| 1–20 | 1 | 1 | Weekly |
| 21–40 | 1 | 2 | Weekly |
| 41–80 | 2 | 3–4 | Weekly; twice-weekly in July–August |
| 81–120 | 3 | 5–6 | Twice-weekly |
| 121–199 | 4–5 | 7–10 | Twice-weekly |
| 200–250 | 4–5 | 10–13 | Three times weekly |
Field sanitation on farms is different: OSHA 1928.110 requires one toilet and one hand-washing facility per 20 workers within a quarter-mile walk when 11 or more employees do hand labor. Source for construction: eCFR 29 CFR 1926.51. The full plain-English version is on the OSHA guide.
How do I adjust the count for alcohol, heat, food and long days?
Multiply by 1.25 and round up when alcohol is served or the temperature will pass 80°F, because people drink more and go more often. Add one hand wash station per 10 units, and one at every food vendor in Bethlehem. For events over 6 hours, either double the count or schedule a mid-event pump-out at $35 per unit, which is cheaper above 8 units. Place units in clusters near the crowd, not one bank at the gate.
- Start with the base. Guests ÷ 100 for standard units, ÷ 75 for deluxe flushing units.
- Multiply for hours. × hours ÷ 4. A 6-hour event is × 1.5; 10 hours is × 2.5. Or keep × 1 and add mid-event pumping.
- Multiply by 1.25 for alcohol or heat, then round up once. A result of 2.34 becomes 3.
- Make 5% accessible. Round up; never fewer than one at a public event; one per cluster in practice.
- Add hand washing. 1 station per 10 units; 1 at each food stand under Bethlehem Health Bureau rules.
- Split into clusters. Stage, food, bar and parking. Each cluster gets its own accessible unit and hand wash station.
How many porta potties do I need: questions people ask
How many porta potties do I need for 100 guests?
Two units for a 4-hour party with alcohol, or one unit for a dry 4-hour event. The base is 100 guests ÷ 100 = 1 unit per 4 hours; alcohol adds 25%, rounded up to 2. If the event is public, one of the two should be the accessible unit. Add one hand wash station if food is served.
How many porta potties for 200 guests?
Three units for a 4-hour event with alcohol (200 ÷ 100 = 2, +25% = 2.5, rounded up to 3) or four units for 6 hours with alcohol. Make one accessible at a public event and add one hand wash station.
How many porta potties for 500 people?
Five units for 4 hours, seven with alcohol, and ten for an 8-hour day without pumping. Make at least one accessible (5% of 10 is 0.5, rounded up to 1; we place one per cluster) and add one hand wash station per 10 units. The City of Bethlehem permit minimum for 500 people is only two units; expect long lines at that number.
How many porta potties for a wedding of 150?
Four: three deluxe flushing units and one accessible unit, for 6 hours with a bar. Flushing units are sized at one per 75 guests per 4 hours because guests linger; 150 ÷ 75 = 2, ×1.5 for 6 hours = 3, +25% alcohol = 3.75, rounded up to 4, with one of those accessible.
How many porta potties does OSHA require for 50 workers?
Two toilets by OSHA Table D-1: 50 ÷ 40 = 1.25, rounded up to 2 (one seat and one urinal per 40 workers above 20). Each PJN3 has a seat and a urinal. We recommend three units for 50 workers on 10-hour days so service stays weekly.
Does the calculator work for a 5K or a parade?
With a change: for a 5K, count runners plus spectators at the start/finish and use a 2-hour window at the start, then size the finish area at the full count for 2 hours. For a parade route, place a cluster of 2 to 4 units every quarter mile at the crowd nodes rather than one big bank.
Official sources cited on this page
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