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Radiant Floor Calculator — PEX Tubing Estimator

Calculate PEX tubing length, rolls, and material costs for radiant floor heating

Units

PEX Tubing Needed

480 ft

Area

300 sq ft

Materials

$1,760

Include sub-floor insulation

Material Estimate

Total PEX Tubing
480 ft
2 rolls (300 ft each)
Heat Output
9,000 BTU
Coverage
300 sq ft

Cost Breakdown

PEX Tubing$360
Manifold (2 zone)$500
Insulation$450
Mixing valve$350
Fittings$100
Materials Total$1,760
Professional Install$1,800 – $3,600

Loop Spacing Guide

SpacingBTU/sq ftBest For
6"40High heat loss, bathrooms
9"30Standard rooms
12"25Well-insulated, supplemental

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Example Calculations

1Standard Bathroom (10×12 ft, 6" spacing)

Inputs

Room10 ft × 12 ft
Spacing6 inches
TubingPEX-A

Result

PEX Needed304 ft (1 roll + header)

120 sq ft / 0.5 ft spacing = 240 ft. Plus 10% turns (264 ft) + 20 ft header = 284 ft. 1 roll of 300 ft.

2Living Room (20×15 ft, 9" spacing)

Inputs

Room20 ft × 15 ft
Spacing9 inches
Zones2

Result

PEX Needed480 ft (2 rolls)

300 sq ft / 0.75 ft = 400 ft. Plus 10% (440 ft) + 40 ft headers (2 zones) = 480 ft.

Frequently Asked Questions

Q

How much PEX tubing do I need for radiant floor heating?

Divide your floor area by the loop spacing (in feet), then add 10% for turns and headers. A 300 sq ft room with 9-inch spacing needs about 440 linear feet of PEX tubing plus 20 feet per manifold zone for headers.

  • 9-inch spacing (standard): floor area / 0.75 ft × 1.10 = total PEX feet
  • 6-inch spacing (high output): floor area / 0.50 ft × 1.10 for bathrooms and exterior walls
  • 12-inch spacing (supplemental): floor area / 1.0 ft × 1.10 for well-insulated spaces
  • PEX comes in 300 ft rolls; plan circuits to avoid joints under the floor
Q

What loop spacing should I use for radiant floors?

Standard 9-inch spacing works for most rooms at 30 BTU/sq ft output. Use 6-inch spacing for bathrooms and high heat loss areas (40 BTU/sq ft), and 12-inch for well-insulated supplemental heating (25 BTU/sq ft).

  • 6" spacing: maximum heat output, best for tile floors over uninsulated slabs
  • 9" spacing: standard for most rooms, provides comfortable even heating
  • 12" spacing: lower output, used with well-insulated homes or as supplemental heat
  • Never exceed 12" spacing; uneven floor temperatures cause cold spots between loops
Q

How much does radiant floor heating cost?

Materials cost $6–$12 per square foot for a hydronic system including PEX, manifold, insulation, and controls. Professional installation adds $6–$12/sq ft. A 300 sq ft room costs $3,600–$7,200 total.

  • PEX-A tubing: $0.65–$0.85/ft; PEX-B: $0.40–$0.55/ft
  • Manifold: $200–$400 per zone including valves and flow meters
  • Sub-floor insulation: $1.25–$1.75/sq ft for R-10 rigid foam panels
  • Mixing valve and pump: $300–$600 depending on system size
Q

What is the best PEX type for radiant floors?

PEX-A (expansion method) is preferred for radiant floors because it has shape memory and fewer fittings. PEX-B works but is stiffer and harder to bend around tight turns. PE-RT is a newer alternative that can be heat-welded.

  • PEX-A: most flexible, can be bent to tighter radius, self-heals from kinks
  • PEX-B: 30–40% cheaper, adequate for straight runs and gentle curves
  • PE-RT: weldable connections, no expansion fittings needed, gaining popularity
  • All three types use oxygen barrier versions for hydronic heating systems

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Last Updated: Jul 13, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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