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Site Welfare Toilets and Washing Stations Calculator

The minimum toilets and washing stations for a site headcount, from the UK workplace welfare code's table or the one OSHA sets for US construction sites.

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  • Every formula cited
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SettingsSettings for this calculationUS
Market
Imperial · sales tax
The most people working on site at one time, all trades together.

Count everyone who will use the facilities at the peak of the job — every contractor's operatives, not only your own — because the facilities are shared and sized for the busiest day, not the average one.

Which published table the counts come from.

The two tables differ in shape: the British one steps up at fixed headcounts and pairs every toilet with a washing station; OSHA's sets a ratio of toilet seats and urinals per worker for construction sites and says nothing numerical about washing. Other countries publish their own ratios.

Toilets, minimum

3 toilets

High confidence

For 30 people, Table 1 of L24 gives 3 toilets and 3 washing stations. The ACoP has a second table for men only, with urinals, which this page does not apply; on a construction site CDM 2015 Schedule 2 asks for facilities that are suitable and sufficient, and L24's numbers are the published measure of sufficient.

Washing stations
3 washing stations
People per toilet
10 people
Then change the inputs to see how far the answer moves.

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How this was calculated

Formula source(s)

  • Workplace (Health, Safety and Welfare) Regulations 1992, Approved Code of Practice L24, Table 1 (mixed use or women): 1 to 5 people, 1 toilet and 1 washing station; 6 to 25, 2 of each; 26 to 50, 3; 51 to 75, 4; 76 to 100, 5; and above 100, one more of each for every 25 people or part of 25
  • Construction (Design and Management) Regulations 2015, Schedule 2: suitable and sufficient sanitary conveniences and washing facilities must be provided or made available at readily accessible places on a construction site
  • 29 CFR 1926.51(c)(1), Table D-1: 20 employees or fewer, 1 toilet; 20 or more, 1 toilet seat and 1 urinal per 40 workers; 200 or more, 1 toilet seat and 1 urinal per 50 workers — and where the facilities will not be used by women, urinals may replace toilet seats down to two-thirds of the minimum number of seats

Inputs used

People on Site at the Busiest Time
30
Table to Apply
Great Britain — Workplace Regulations ACoP L24, Table 1

Intermediate steps

Washing stations
3 washing stations
People per toilet
10 people
Final result3 toilets

Confidence note: For 30 people, Table 1 of L24 gives 3 toilets and 3 washing stations. The ACoP has a second table for men only, with urinals, which this page does not apply; on a construction site CDM 2015 Schedule 2 asks for facilities that are suitable and sufficient, and L24's numbers are the published measure of sufficient.

What this calculation does not cover

  • These are minimum numbers of fittings, not a welfare design. Separate facilities for men and women, an accessible facility, heating, lighting, ventilation and a regular cleaning and servicing schedule are all required on top.
  • Washing facilities need hot and cold or warm running water, soap and a means of drying, and should be next to the toilets and near changing areas; a basin count alone does not describe them.
  • Rest areas, drinking water, changing rooms and somewhere to store and dry clothing are part of site welfare too and are not counted here.
  • The count is for people working at one time. A site whose peak is short but intense is sized for the peak.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-21 · v1.0.0

Regulatory standards & verification citations3
  1. Workplace (Health, Safety and Welfare) Regulations 1992, Approved Code of Practice L24, Table 1 (mixed use or women): 1 to 5 people, 1 toilet and 1 washing station; 6 to 25, 2 of each; 26 to 50, 3; 51 to 75, 4; 76 to 100, 5; and above 100, one more of each for every 25 people or part of 25
  2. Construction (Design and Management) Regulations 2015, Schedule 2: suitable and sufficient sanitary conveniences and washing facilities must be provided or made available at readily accessible places on a construction site
  3. 29 CFR 1926.51(c)(1), Table D-1: 20 employees or fewer, 1 toilet; 20 or more, 1 toilet seat and 1 urinal per 40 workers; 200 or more, 1 toilet seat and 1 urinal per 50 workers — and where the facilities will not be used by women, urinals may replace toilet seats down to two-thirds of the minimum number of seats
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Your workspace

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How to calculate site welfare toilets and washing stations in 3 steps

  1. People on Site at the Busiest TimeThe most people working on site at one time, all trades together.
  2. Table to ApplyWhich published table the counts come from.
  3. Toilets, minimumThe tool computes the toilets, minimum from those figures and shows the formula, its sources, and a confidence rating alongside it.

Toilets, minimum by people on site at the busiest time

Page defaults, not your figures above.

People on Site at the Busiest TimeToilets, minimum (toilets)
51
102
202
503
1005
2009

Frequently asked questions

Who counts towards the number?
Everyone who will be working on site at the same time and using the facilities — every trade and every contractor, not only the principal contractor's own people — at the busiest point of the job. Facilities sized for the average headcount run out on exactly the days they are needed most.
Why does the US table give fewer toilets at 200 workers than at 199?
Because Table D-1 changes its ratio at 200, from one seat and one urinal per 40 workers to one of each per 50. Read literally, 199 workers need five seats and 200 need four. The table sets a minimum, not a target, and many employers simply keep the 40-worker ratio as the site grows rather than remove facilities as more people arrive.
Do the numbers change for a small or short job?
No: the British table starts at one toilet and one washing station for up to five people, and CDM 2015 applies to every construction site regardless of size. On a short job the facilities may be portable or shared with an occupied building by agreement, but they still have to be there from the first day. OSHA's table likewise starts at one toilet for up to 20 workers.
Are washing facilities counted in the US too?
OSHA's construction standard requires washing facilities where the work needs them — with paints, coatings, herbicides, lead and similar substances, for instance — but sets no ratio of basins to workers, so this page counts only toilets and urinals for a US site. The British table pairs each toilet with a washing station for every job.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.