OSHA Job-Site Toilet Calculator
OSHA 29 CFR 1926.51(c) sets exact toilet ratios for construction sites: 1 toilet up to 20 workers, then 1 seat and 1 urinal per 40 workers, relaxing to per-50 at 200+. Enter your crew size for the legal minimum — and the larger count experienced supers actually order.
The gap matters: OSHA's table assumes nothing about service frequency, but a weekly-pumped porta potty realistically serves about 10 workers. The result is a compliance-ready spec you can hand independent local rental providers — or an inspector.
How this works
The legal minimum comes directly from OSHA 29 CFR 1926.51(c) Table D-1, the sanitation standard for construction: sites with 20 or fewer workers need at least 1 toilet; sites with more than 20 need 1 toilet seat and 1 urinal per 40 workers; and sites with 200 or more workers need 1 toilet seat and 1 urinal per 50 workers. Standard porta potties count as a toilet seat, and units with built-in urinals cover both fixtures. Under 1926.51(c)(4), mobile crews don't need on-site units if transportation to nearby toilet facilities is immediately available.
Alongside the legal floor we show the industry-recommended count: 1 weekly-serviced unit per 10 workers per 40-hour week — the sizing rule sanitation providers use so units stay usable between weekly pump-outs. The two numbers diverge sharply on bigger crews (a 100-worker site passes inspection with 3 seats and 3 urinals but runs comfortably on 10 serviced units), and the difference is the gap between technical compliance and a site where crews don't leave to find restrooms. The related 1-stall-per-50-guests event math doesn't apply here — job-site sizing is driven by service frequency, not peak surges.
For projects running a month or longer, we surface long-term pricing context: providers price extended rentals in 28-day periods with weekly service bundled, published restroom-trailer long-term rates run $5,299–$9,999 per 28 days, and multi-month sites often qualify for volume pricing. This is a planning tool built on the published standard, not legal advice — your state plan or project owner may impose stricter requirements, and independent local rental providers confirm final counts and service schedules for your site.
Estimates only — independent local providers quote their own pricing. Data last reviewed 2026-07.
Frequently Asked Questions
How many porta potties does OSHA require on a construction site?
Per 29 CFR 1926.51(c) Table D-1: 1 toilet for 20 or fewer workers; 1 toilet seat plus 1 urinal per 40 workers for sites over 20; and 1 seat plus 1 urinal per 50 workers at 200+. A standard porta potty counts as a toilet seat, and units with urinals satisfy both fixture types.
Is the OSHA minimum actually enough units?
Legally yes, practically often no. OSHA's table says nothing about pump-out frequency, and a weekly-serviced unit realistically supports about 10 workers per 40-hour week. Most experienced contractors order to the 1-per-10 rule — it costs a little more and eliminates the mid-week overflow complaints that kill morale.
Do mobile crews need porta potties at every location?
Not necessarily. Under 1926.51(c)(4), mobile crews working at normally unattended locations are exempt if transportation to nearby toilet facilities is immediately available. Document which facilities crews use — that's the first thing a compliance officer asks — and consider one unit at your staging yard.
What does long-term job-site rental cost?
Extended rentals are priced per 28-day period with weekly service typically bundled. Standard porta potties are the budget option; restroom trailers for site offices and supervision teams run $5,299–$9,999 per 28 days at published rates. Multi-month projects should ask about volume and duration discounts — get quotes from providers near the site to cut delivery fees.
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