Overview
This calculator estimates the pipe demand for a hydronic underfloor heating system from the heated floor area, tube spacing, maximum loop length, extra connection runs, and waste allowance. It is useful when you need a first material estimate before choosing manifold size or ordering pipe rolls. The result helps you see whether the floor can be covered in one circuit or needs several shorter loops.
Use cases
- Sizing pipe for a room or zoneEstimate how many meters of pipe are needed for a single room, open-plan area, or heating zone before you place an order.
- Checking manifold circuit countSee how many loops are needed so each circuit stays below the maximum length you set for the manifold.
- Comparing spacing optionsTest different tube spacing values to understand how a tighter layout increases pipe demand and circuit count.
- Planning a renovation runAdd connection lengths and waste to build a realistic takeoff for a retrofit where the manifold is not next to the heated area.
How it works
- 1
Enter the heated floor area in square meters.
- 2
Set the pipe spacing in centimeters.
- 3
Specify the maximum allowed loop length.
- 4
Add the extra connection length for runs to and from the manifold.
- 5
Include a waste percentage for cuts, bends, and layout margin.
Examples
Living room layout
Input: Area: 34 m2, spacing: 15 cm, max loop: 95 m, extra connection: 8 m, waste: 7%
Output: Estimated pipe demand is about 265 m total, which splits into 3 loops with an average loop length around 88 m.
Typical calculation for one medium-sized room served by a nearby manifold.
Open-plan ground floor
Input: Area: 82 m2, spacing: 10 cm, max loop: 100 m, extra connection: 12 m, waste: 10%
Output: Estimated pipe demand is about 922 m total, requiring 10 loops with an average loop length close to 92 m.
Shows how tight spacing and a large area quickly increase the number of circuits.
Bathroom extension
Input: Area: 9.5 m2, spacing: 20 cm, max loop: 70 m, extra connection: 6 m, waste: 5%
Output: Estimated pipe demand is about 59 m total, so a single loop is sufficient and stays within the length limit.
Useful for a small zone where one circuit can cover the floor comfortably.
FAQ
What does the pipe spacing change in the result?
Spacing determines how densely the pipe is laid. Narrow spacing increases total pipe length and usually raises the loop count, while wider spacing reduces both.
Why does extra connection length matter?
It covers the route from the manifold to the heated area and back. If you skip it, the estimate will be too short, especially in larger houses or retrofit projects.
What if my room has an awkward shape?
The calculator assumes a simplified layout. Irregular rooms, cut-outs, columns, and edge zones can increase real pipe demand, so treat the result as a planning estimate.
How do I interpret the loop length result?
The average loop length shows how the total pipe may be distributed across circuits. If the average is close to your limit, plan for more loops or shorter runs.
Can I enter one total area for several rooms?
Yes, but only if they belong to the same heating zone and use the same spacing and loop limit. If rooms need different settings, calculate them separately.
Why does the calculator ask for waste?
Waste accounts for offcuts, turns, and layout adjustments. Omitting it can leave you short of pipe when the floor is being installed.