Commercial Load Calculator

Commercial Plumbing Load Calculator is a professional water demand calculation tool for plumbing engineers, plumbing contractors, and mechanical estimators sizing commercial water supply systems. Convert WSFU (Water Supply Fixture Units) to peak GPM demand using the printed Hunter curve of IPC Table E103.3(3), with separate columns for flush tank and flushometer valve systems. Complete water system design in minutes, not hours. Works 100% offline on the job site.

FEATURES
• Printed Hunter Curve: Peak demand read from IPC Table E103.3(3) (Appendix E) — both columns, supply systems predominantly for flush tanks or for flushometer valves, with linear interpolation between printed rows up to 5,000 WSFU
• Direct WSFU Entry: Already totaled fixture units from your fixture schedule? Enter WSFU directly and get the table demand in GPM
• 12 Building Type Presets: Apartment buildings, offices, hotels/motels, restaurants, schools, hospitals, retail stores, warehouses, churches/assembly, gyms, laundromats, and barber/beauty shops — planning-level WSFU densities derived from IPC Table 403.1 minimum fixtures and Table E103.3(2) fixture values, with the unit of count shown for each type
• Hunter Curve Analysis: Visual demand curve drawn through the printed table rows, with simultaneous use factor and demand zone classification
• Result Notes: Every result cites the exact table column used and flags preset estimates so you know what to verify for permit work

HOW IT WORKS
1. Select a building type preset — or Direct WSFU Entry if you have a fixture-count total
2. Enter the unit count (dwelling units, guest rooms, seats, beds, 1,000 sq ft…) or the WSFU total
3. Choose the system type: flush tanks or flushometer valves
4. The app totals WSFU and reads peak GPM demand from IPC Table E103.3(3)
5. Export to PDF with the table reference for engineering review

PERFECT FOR
• Plumbing engineers designing commercial water systems
• Plumbing contractors estimating water supply piping size
• MEP engineers and mechanical estimators
• Plumbing apprentices studying commercial load calculations
• Building code officials verifying system compliance
• Facilities managers understanding water demand

OPTIONAL PRO UPGRADE — $2.99 ONE-TIME IN-APP PURCHASE
The following features require a separate one-time in-app purchase. They are not required to use the calculator:
• Unlimited saved calculation history
• PDF export of results
• Dark theme
• Ad-free experience

STANDARDS & COMPLIANCE
Demand estimation per IPC (International Plumbing Code) Appendix E, Table E103.3(3) — Hunter probability curve, flush tank and flushometer valve columns. Building presets are planning estimates based on IPC Table 403.1 minimum fixture counts and Table E103.3(2) fixture unit values; for permit submittals, total WSFU from actual fixture counts.

OFFLINE & PRIVACY
• Works 100% offline - no internet connection needed for calculations
• No account or login required - instant access
• No data collection - all calculations stay on your device
• No cloud sync or data sharing - complete privacy

Part of PlumbTools Suite - professional plumbing code calculators and tools for plumbers, contractors, and engineers. Speed up system design, eliminate calculation errors, and ensure code compliance with plumbing calculator apps.

Recent changes:
Added a link to TradeTools — the one-app version of this calculator and 61 more, for HVAC, electrical, plumbing, fire protection, solar and carpentry. Nothing else changed.