Canadian WSFU Pipe Sizing Calculator – NPC 2020
Add plumbing fixtures to calculate NPC 2020 fixture units, then convert the total directly to a minimum nominal water pipe size at 4, 5, 8 or 10 ft/s.
NPC 2020 hydraulic load totals
Cold-water load
2.7 FU
Hot-water load
0.5 FU
Combined hydraulic load
2.9 FU
NPC 2020 Table A-2.6.3.1.(2)-F
Fixture Units to Water Pipe Size
The calculator uses the combined fixture-unit total above by default. If you already know the fixture units served by a particular pipe section, enter that value directly below.
Minimum nominal size
1/2"
Load being sized
2.9 FU
Table capacity
3.5 FU
at 5 ft/s
Table flow
0.23 L/s
83% of listed FU capacity
This is a Table A-2.6.3.1.(2)-F lookup for the NPC 2020 Average Pressure Loss Method. Choose a velocity consistent with the pipe and fitting manufacturer requirements. Water-service and complete distribution-system design must also account for the applicable NPC method, pressure, developed length, elevation, equipment losses and other water demands.
Turn the calculation into a complete design workflow
Use the free result as a quick engineering check, then continue into MEPFlow for connected system design, sizing and project calculations.
How the Canadian WSFU Pipe Sizing Calculator – NPC 2020 Works
This calculator hard-codes the National Plumbing Code of Canada 2020 water-distribution fixture-unit values from Table 2.6.3.2.-A. Select private or public use, add each fixture and quantity, and the calculator applies the corresponding cold-water, hot-water and combined hydraulic load.
Direct-flush urinals and water closets are not calculated by multiplying a single fixture value. Their loads increase cumulatively as more valves are connected, so MEPFlow applies Tables 2.6.3.2.-B and 2.6.3.2.-C automatically.
After the fixture-unit tally, the pipe-sizing section uses NPC 2020 Table A-2.6.3.1.(2)-F from the Average Pressure Loss Method. Choose 4, 5, 8 or 10 ft/s and the calculator returns the smallest nominal pipe size whose listed fixture-unit capacity is equal to or greater than the load being sized.
If you already know the fixture units served by a pipe section, enter them directly in the pipe-sizing field without rebuilding the fixture list. The table lookup is a sizing aid within the NPC method; final design still requires the applicable pressure, developed length, elevation, device-loss and manufacturer velocity checks.
Calculation basis
NPC 2020 FU tally → Table A-2.6.3.1.(2)-F → minimum nominal pipe size
When to Use This Calculator
- Canadian water supply pipe sizing from WSFU
- NPC 2020 fixture-unit calculations
- Quick fixture-units-to-pipe-size lookup
- Private and public plumbing fixture schedules
Engineering Checks Before Final Design
- The calculator is specifically based on NPC 2020; verify the code edition and amendments adopted for the project jurisdiction.
- Choose a velocity consistent with the manufacturer's requirements for the selected pipe and fittings.
- Commercial clothes washers and commercial dishwashers are not assigned a generic fixture value because NPC 2020 directs the designer to manufacturer recommendations.
- The Table F result does not replace the complete NPC Average Pressure Loss Method, water-service pressure analysis or section-by-section distribution sizing.
Frequently Asked Questions
Can I size a water pipe directly from fixture units?
Yes. Enter the fixture units served and select the design velocity. The calculator uses NPC 2020 Table A-2.6.3.1.(2)-F to return the smallest listed nominal pipe size with sufficient fixture-unit capacity.
Are the fixture values hard-coded?
Yes. The calculator uses National Plumbing Code of Canada 2020 Table 2.6.3.2.-A values for private and public use and automatically applies the direct-flush cumulative rules in Tables 2.6.3.2.-B and -C.
Which velocity should I use for pipe sizing?
NPC 2020 says to use the velocity column consistent with the manufacturer's requirements for the pipe and fittings chosen. This calculator exposes the four Table F columns: 4, 5, 8 and 10 ft/s.
Does the calculator size every branch in a plumbing system?
No. It sizes the fixture-unit load entered or calculated at one point. A complete system is sized section by section as fixture-unit loads accumulate along the distribution network.
Are WSFU the same as GPM?
No. Fixture units are a diversity-based hydraulic-load index. Table A-2.6.3.1.(2)-F provides both fixture-unit capacity and corresponding flow for each nominal size and velocity.
Engineering References
MEPFlow uses public engineering references to document the calculation basis. Always verify the final design against the standard, code edition and manufacturer data applicable to your project.