Inputs
Example data table
| Scenario | Type | Floors | Occupants / Units | Contingency | WCs | Urinals | Lavatories | Drink Fountains |
|---|---|---|---|---|---|---|---|---|
| Office example | Office | 3 | 70 male, 50 female | 10% | Male 2, Female 3 | 2 | 4 | 2 |
| Residential example | Residential | 8 | 24 units | 5% | Total 26 | 0 | 26 | 0 |
Formula used
Occupancy-based: Each fixture count is calculated as Ceiling(Occupants ÷ Ratio). Ratios are entered as people per fixture.
Unit-based: Each fixture count is calculated as Ceiling(Units × Fixtures per unit).
Contingency: Planning uplift is applied as Ceiling(Base count × (1 + Contingency%)).
Per-floor schedule: Ceiling(Total ÷ Floors) is shown for preliminary distribution.
Accessibility planning: Recommended accessible water closets = max(1, Ceiling(Total WCs × Accessibility%)).
How to use this calculator
- Select the building type and enter the number of floors.
- Choose occupancy-based for public buildings or unit-based for residential.
- Enter occupants by gender or enter dwelling units and per-unit fixtures.
- Optional: enable custom ratios to match a specific standard.
- Press calculate to view totals above and download schedules.
Occupant Load Inputs and Assumptions
Start with a realistic design population for each floor. Separate male and female counts when possible, because fixture demand is not always symmetric. If gender split is unknown, document the assumed split used for calculations. If your program includes visitors, add them to the peak period population rather than average daily headcount. For mixed-use buildings, calculate each use separately and combine schedules during coordination at milestones.
Fixture Ratios and Code Alignment
The calculator uses “people per fixture” ratios to estimate counts quickly. Lower ratios mean more fixtures. Defaults suit concept design, then replace them with ratios from your governing plumbing code, authority guidance, or client standards before issuing tender documents. Urinals may be set to zero where they are not permitted or desired.
Floor Distribution and Core Planning
Totals are converted to a per-floor schedule using ceiling division. This creates a conservative starting point for toilet-room stacking, riser sizing, and shaft coordination. After zoning is confirmed, redistribute fixtures toward high-demand areas such as cafeterias, reception zones, or public lobbies. Validate that cleaning access, ventilation paths, and drain runs remain practical.
Accessibility and Inclusive Layout Targets
An accessibility percentage is applied to total water closets to recommend an inclusive minimum. Treat this as a planning target, not a compliance certificate. Confirm turning radii, grab bar clearances, door swings, and route widths during layout, and coordinate with local accessibility requirements. Consider family or assisted toilet rooms where public traffic is high.
Procurement Scheduling and Risk Buffers
Contingency increases base quantities and rounds up to whole fixtures. Use it to cover design evolution, tenant changes, and lead-time risks. When exporting schedules, tag fixtures by type, flush valve style, and finish, then align submittals with floor-by-floor construction sequencing to avoid storage and damage. Keep spare cartridges and seats for early maintenance needs.
FAQs
Which method should I choose?
Use occupancy-based for offices, schools, and public areas. Use unit-based for apartments or hotel-style units where fixtures scale with unit count.
Are default ratios compliant everywhere?
No. Defaults are for early planning only. Replace them with your local plumbing code ratios and any authority amendments before finalizing drawings.
Why does the calculator round up?
Fixtures must be whole units. Ceiling rounding avoids under-sizing and supports early-stage allowances for peak usage and layout constraints.
How should I use the per-floor schedule?
Treat it as a conservative starting point. Distribute fixtures where demand occurs, then update per core, tenant zone, or toilet-room cluster.
What does the accessibility percentage mean?
It recommends a minimum number of accessible water closets as a planning target. Final compliance depends on stall geometry, clearances, routes, and local accessibility rules.
Can I export results for procurement?
Yes. Use CSV for quantity takeoff and vendor comparisons. Use the PDF for approvals and coordination meetings with the design and construction teams.