Underfloor Heating Calculator
Estimate pipe length and heating power for your system.
How does the underfloor heating calculator work?
This calculator helps you plan an underfloor heating system by estimating two key values: total heating power and required pipe length. Enter the room area, choose the pipe spacing (typically 15–30 cm), and set the desired heating power per square meter (usually 60–100 W/m² for well‑insulated rooms). The calculator computes the total wattage and the meters of pipe needed to cover the floor area at the given spacing.
How to use the Underfloor Heating Calculator
Enter the room area in square meters or square feet, select the pipe spacing from the dropdown, and input the desired heat output per square meter. Click "Calculate" to instantly see the total heating capacity in watts and the total pipe length in meters. Use these numbers to size your manifold, circulator pump, and to order the correct amount of pipe.
Example calculation
A 20 m² room with 20 cm pipe spacing and 80 W/m²: Total power = 20 × 80 = 1,600 W (1.6 kW). Pipe length ≈ 20 ÷ 0.20 = 100 m (approximately 5 linear meters of pipe per square meter at 20 cm spacing). The calculator handles both metric and imperial inputs.
Frequently Asked Questions
What pipe spacing should I choose?
Tighter spacing (15 cm) gives more even heat distribution and higher output, ideal for rooms with high heat loss. Wider spacing (25–30 cm) uses less pipe and is suitable for well‑insulated spaces. 20 cm is the most common choice for residential rooms.
How many watts per square meter do I need?
A well‑insulated modern home typically needs 60–80 W/m². Older buildings or rooms with large windows may require 100 W/m² or more. The calculator lets you adjust this value to match your specific building characteristics.