Inputs
How to use this calculator
- Enter total occupancy from your occupant load calculation.
- Set restroom groups to match floors or separate zones.
- Select a ratio preset, then tune ratios if needed.
- Adjust the male percentage when project demographics differ.
- Click Calculate to view totals and download reports.
Formula used
The calculator splits occupancy by gender, then applies ratios as people per fixture. Each fixture count rounds up to ensure minimum coverage.
- Male occupants per group = (Total occupancy / Groups) × (Male % / 100)
- Female occupants per group = (Total occupancy / Groups) − Male occupants per group
- Fixtures per group = ceil(Occupants per group / Ratio)
- Total fixtures = Fixtures per group × Groups
- Accessible stalls = max(Minimum, ceil(Total WC × Accessible % / 100))
Ratios vary by code edition, use type, and local amendments.
Example data table
| Scenario | Occupancy | Groups | Male % | Male WC | Urinals | Female WC | Lavatories | Fountains |
|---|---|---|---|---|---|---|---|---|
| Office example (preset) | 150 | 1 | 50 | 2 | 1 | 2 | 8 | 2 |
| Education example (preset) | 420 | 2 | 45 | 4 | 6 | 6 | 14 | 4 |
| Assembly example (preset) | 1200 | 3 | 55 | 6 | 30 | 18 | 18 | 6 |
Examples assume the selected preset ratios and round up.
Occupant load and design intent
This calculator converts a planned occupant load into a starting fixture count for toilets, urinals, lavatories, and drinking fountains. Use the same occupant load applied to life-safety planning, then confirm whether it represents peak simultaneous use or an average staffing level. Entering a realistic load is the biggest driver of totals and the plumbing capacity that follows.
Gender distribution and zoning
Occupancy is split by the male percentage, with the remainder treated as female for planning. When floors or wings operate independently, set restroom groups to distribute demand. The tool divides total occupancy by groups, calculates fixtures per group, then multiplies to totals. This helps prevent under-sizing on one level when the building is segmented.
Fixture ratios and rounding rules
Ratios are entered as people per fixture. For each fixture type, the count is computed as the ceiling of occupants divided by the ratio, so fractional results always round up. Rounding up protects minimum coverage and mirrors typical code tables that require whole fixtures. Presets provide starting values, but you should adjust ratios to match your occupancy classification and local amendments.
Accessibility planning and documentation
Accessible stalls are estimated as a percentage of total water closets, with an optional minimum. This is an early coordination aid, not a final accessibility determination. Use it to flag when additional accessible stalls may be needed as counts increase. Record assumptions in project notes and verify final requirements during plan review and detailing.
Using exports for coordination
Download the CSV for takeoffs, schedules, and spreadsheet checks, and use the PDF for sharing with architects, clients, and reviewers. Each export summarizes inputs, per-group assumptions, and rounded totals, making it easier to reconcile changes when occupant load, demographics, or zoning shifts. For bid packages, consistent documentation reduces RFIs and supports quick comparisons between design iterations, especially when multiple restroom cores are being value-engineered across phases and disciplines. Saving exports with drawings helps teams keep fixture counts aligned with the latest program.
FAQs
Which code does this calculator follow?
It provides configurable ratios and presets for planning. Enter the fixture ratios required by your adopted plumbing code and local amendments. Use the results as a documented calculation, then confirm final compliance during plan review.
How do restroom groups affect the totals?
Groups split the occupancy evenly, calculate fixtures per group with rounding up, then multiply back to totals. This helps model multiple floors or zones that need their own coverage rather than relying on a single shared restroom core.
Should I include urinals for every project?
Use urinals when they are allowed and appropriate for the male restroom program. If you are planning unisex facilities or codes that limit substitutions, uncheck urinals and size water closets using the required ratios.
Why does the calculator always round up?
Fixtures must be whole numbers, and minimum requirements typically cannot be met with fractions. Ceiling rounding ensures you do not undercount when the occupant load does not divide evenly by the selected ratio.
How is the accessible stall count calculated?
Accessible stalls are estimated as a percentage of total water closets, with an optional minimum. This is a coordination aid. Confirm the required number and distribution of accessible stalls using the accessibility standard and jurisdictional guidance.
Can I use the exports in submittals?
Yes. The CSV supports schedules and quantity checks, while the PDF provides a clean summary of assumptions and totals. Attach exports to coordination packages so reviewers can trace fixture counts back to the same occupant load and ratios.