How Many Portable Toilets Do I Need for My Event? (Calculator Guide)

Get the toilet count wrong at an event and you’ll know within the first hour. Queues form fast and they don’t clear. The good news is that the maths is simple. You need a base ratio and three things that change it: event length, alcohol, and gender split. This guide gives you a formula you can run in under a minute, plus worked examples for common UK event sizes.

The base formula

Start here: 1 toilet per 50 guests for an event lasting up to 4 hours. The UK events industry works from that baseline.

It holds up well for daytime events with food but no alcohol. Think christenings, corporate lunches and school fetes. Then add capacity for each condition below:

• Event runs longer than 4 hours: add 1 unit per additional 2 hours
• Alcohol is served: increase ratio to 1 per 35 guests. People drink more, queue less patiently, and use the loo more often
• Mixed outdoor/muddy site: add 1 extra unit as a buffer. People avoid queuing in mud and hold on, then all go at once
• Guests are mostly women: shift the ratio toward 60/40 in favour of ladies’ units, because female toilet visits typically take longer

Worked examples

Each example below applies the rules above step by step. For example, the first one adds alcohol and a long day to a wedding.

Example 1: 100-guest garden wedding reception, 6 hours, alcohol served

• Base: 100 guests ÷ 35 (alcohol ratio) = 2.9, round up to 3
• Duration: 6 hours is 2 hours over the 4-hour baseline = add 1
• Total: 4 standard units, or a 2+1 luxury trailer (2 ladies, 1 gents, giving effectively 3 cubicles plus a urinal)

Example 2: 250-guest music festival day, 8 hours, alcohol served, outdoor/field site

• Base: 250 ÷ 35 = 7.1, round up to 8
• Duration: 8 hours is 4 hours over baseline = add 2
• Muddy site buffer: add 1
• Total: 11 units. A mix of standard cubicles and 2-3 urinal units is usually more cost-effective than all cubicles. Urinals cost £40-£60 for the weekend versus £45-£75 for a standard cubicle, and they clear queues faster for men

Example 3: 40-guest christening, 3 hours, no alcohol

• Base: 40 ÷ 50 = 0.8, round up to 1
• No duration or alcohol adjustment needed
• Total: 1 standard unit, or 1 disabled-access unit if you want a single unit that covers accessibility too (from £65-£95 for the weekend)

Example 4: 500-guest corporate outdoor event, full day (10 hours), alcohol at evening reception only

• Base: 500 ÷ 50 (daytime, no alcohol) = 10
• Evening uplift: treat the last 3 hours as the alcohol-service window and add 15% capacity = add 2
• Duration: 10 hours is 6 hours over baseline = add 3
• Total: 15 units. At this scale, most UK suppliers will recommend at least one welfare unit alongside standard cubicles. Staff and organisers then have a base with running water

Don’t forget accessibility

UK guidance and most venue contracts expect at least one accessible unit for events over roughly 100 guests. This applies whether or not you know a wheelchair user is coming. Budget one disabled-access unit into any event above that size. It has more space inside, so it also works for baby changing if you have no dedicated unit.

Staff and crew need their own toilets

Your festival, market or multi-day event may have catering staff, security or stallholders on site. If so, work out their toilet needs separately from guest numbers. Use the same base ratio. Crew toilets usually sit away from public units. Staff also change over during a shift. Since people come and go, the same ratio applies even though headcount looks smaller at any one moment.

When to round up rather than down

Sometimes your guest count sits right on a threshold, say 48 or 52 guests against the 50-per-unit ratio. Always round up, because the cost difference between 1 and 2 standard units for a weekend is typically £45-£75. That is small to the damage a queue does to your event.

Under-ordering is the single most common mistake event organisers make. It almost always happens because they planned for the guest list. Instead, plan for real attendance plus any day guests, contractors or evening-only arrivals.

Getting the right mix, not just the right count

However many units you need in total, split them across unit types. Don’t order identical cubicles. A sensible mix for a mid-size event with alcohol is roughly 60% standard cubicles. Add 25% urinals (men’s events) or extra ladies’ cubicles (mixed events), and at least one accessible unit.

Send your guest count, event type and date via our online quote form. You’ll get a recommended unit mix and confirmed pricing back by email within 30 minutes, Monday to Saturday. There is no need to work out the maths yourself.

Where we deliver

We supply units across the UK. For example, see our pages for portaloo hire in London, portaloo hire in Manchester, portaloo hire in Barking and Dagenham, portaloo hire in Enfield and portaloo hire in Kent. Each page explains local delivery and gives a clear price guide.

Also, compare standard portaloo hire with current hire prices before you book. Then send us your details through the online quote form and we will reply within 30 minutes, Monday to Saturday.