Underfloor Heating
UFH Manifold Port Count Calculator
Manifold size from the number of loops
Updated July 12, 2026 · Live
What this tool does
Works out the manifold port count and recommended manifold size from the number of underfloor heating loops.
Enter the number of loops; the calculator returns the ports needed and the recommended manifold size.
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Formula Used
Works out the manifold port count and recommended manifold size from the number of underfloor heating loops. It runs entirely in your browser and shows the working, so you can check every step against your own figures.
How the ufh manifold port count calculator works
A manifold has one flow and one return connection for each loop, so the port count equals the number of loops. Manifolds are sold in whole-port sizes, typically two to twelve, so the tool picks the smallest standard manifold that takes all your loops and shows any spare ports for a future zone.
What you enter
Enter the number of loops; the calculator returns the ports needed and the recommended manifold size. Every field is editable, and the result recalculates the moment you change a value.
Reading the result
Match the manifold to the loop count from the pipe-length tool, and leave a spare port or two if you might extend the heated area later. Each loop needs a flow meter and an actuator head at the manifold.
Safe by design
This tool sizes pipe, manifold, coverage and cost. It never sets flow temperatures or heat-source settings — commissioning the system is a qualified heating engineer’s job.
Assumptions and limits
This counts ports from loops. It does not size the manifold’s flow rate, the mixing valve or the pump, which depend on the heat demand and flow temperature — commissioning work for a heating engineer.
Using it with the rest of BuildMetricLab
This calculator is one step in planning the job. Pair it with the related tools in this category and across BuildMetricLab to go from a single figure to a full costed plan — a sizing figure feeds a cost estimate, a cost estimate feeds a project budget, and each result carries straight into the next tool. Every BuildMetricLab tool runs entirely in your browser — no sign-up, nothing sent to a server, and the formula is shown on the page so the maths can be audited.
Sources & methodology
Works out the manifold port count and recommended manifold size from the number of underfloor heating loops. Every result is calculated from the values you enter, all inputs are editable, and no time-sensitive prices or rates are embedded.
Frequently asked questions
How many manifold ports do I need?
One per loop — each loop uses a flow and a return connection. Six loops need a six-port manifold.
Should I leave spare ports?
A spare port or two is cheap insurance if you might extend the heated area or add a zone later.
What else fits on the manifold?
Each loop typically has a flow meter to balance it and an actuator head driven by the room thermostat.
Does this size the pump?
No — the pump, mixing valve and flow rate depend on the heat demand and are set during commissioning by a heating engineer.
Spotted something off?
Calculations or display — let us know.