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ASTM F876 / ASTM F877 PEX SDR-9 CTS True ID: 0.475" (12.07 mm) 160 PSI @ 73°F

1/2" PEX Pipe Volume & Capacity Calculator

Standard 1/2" SDR-9 PEX tubing has an inner diameter of 0.475 inches, holding 0.0092 US gallons (0.114 liters per meter) per linear foot. Part of our universal Pipe Volume Calculator and Water Pipe Volume tools.

Presets:
Calculated Result

Total Liquid Capacity

Internal Holding Volume
0.9205 US gallons
≈ 3.485 litres

Unit Conversions

US Gallons 0.9205 gal
Litres 3.485 L
Cubic Feet (ft³) 0.1231 ft³
Cubic Inches (in³) 212.65 in³
Imperial Gallons 0.7665 UK gal
Cubic Meters (m³) 0.0035 m³
Filled Water Weight 7.7 lbs (3.5 kg)
Linear Capacity Rate 0.0092 gal/ft

Calculations are based on cylindrical formula \(V = \pi r^2 L\). Verify dimensions against manufacturer specs for code submittals.

Pre-Calculated Capacity Table

1/2" PEX Tubing Quick Reference Sizing Chart

Instant capacity and weight lookup table for common PEX coil lengths and radiant floor heating loops.

Coil Length (Ft) US Gallons Liters Cubic Feet (ft³) Water Weight (lbs) Dry Tubing (lbs) Total Wet Weight
1 ft 0.009 gal 0.03 L 0.001 ft³ 0.1 lbs 0.1 lbs 0.1 lbs
5 ft 0.046 gal 0.17 L 0.006 ft³ 0.4 lbs 0.3 lbs 0.7 lbs
10 ft 0.092 gal 0.35 L 0.012 ft³ 0.8 lbs 0.5 lbs 1.3 lbs
25 ft 0.230 gal 0.87 L 0.031 ft³ 1.9 lbs 1.4 lbs 3.3 lbs
50 ft 0.46 gal 1.7 L 0.06 ft³ 3.9 lbs 2.7 lbs 6.6 lbs
100 ft 0.92 gal 3.5 L 0.12 ft³ 7.7 lbs 5.4 lbs 13.1 lbs
200 ft 1.84 gal 6.9 L 0.25 ft³ 15.4 lbs 10.8 lbs 26.2 lbs
300 ft 2.76 gal 10.4 L 0.37 ft³ 23.1 lbs 16.2 lbs 39.3 lbs
500 ft 4.60 gal 17.4 L 0.61 ft³ 38.5 lbs 27.0 lbs 65.5 lbs
1000 ft 9.20 gal 34.7 L 1.23 ft³ 77.0 lbs 54.0 lbs 131.0 lbs
Engineering Formula

How to Calculate 1/2" PEX Tubing Volume Manually

Step-by-step mathematical demonstration using cylinder geometric principles and SDR-9 ASTM specifications.

Step 1

Determine the Internal Radius (r)

Nominal size is 1/2", but true inner diameter is 0.475 inches.

r = ID / 2 = 0.475 / 2 = 0.2375"
Step 2

Calculate Cross-Sectional Area (A)

Compute circular cross-section area using $A = \pi \times r^2$:

A = \pi \times (0.2375)^2 = 0.1772 sq in
Step 3

Calculate Linear Foot Volume

Multiply cross-sectional area by 12 inches (1 linear foot):

V_linear = 0.1772 \times 12 = 2.126 cu in/ft
Step 4

Convert to US Gallons & Liters

Divide cubic inches by 231 (cubic inches in 1 US Gallon):

Gallons/Ft = 2.126 / 231 = 0.0092 Gal/Ft
Technical Specifications

1/2" PEX SDR-9 Engineering Profile

Physical dimensions, pressure thresholds, and hydraulic velocity limits.

Outside Diameter (OD)
0.625 inches
15.9 mm
Inside Diameter (ID)
0.475 inches
12.07 mm
Wall Thickness
0.075 inches
SDR-9 Tolerance
Max Recommended Flow
3 GPM
At safe 8 ft/s PEX limit
Working Pressure
160 PSI
At 73.4°F (100 PSI @ 180°F)
Max Temperature Limit
200°F
93°C continuous

Common Plumbing & Radiant Applications for 1/2" PEX:

  • Residential hot & cold water branch lines
  • Radiant underfloor heating loops
  • Plumbing manifold home-run circuits

Primary Use Case: Standard branch lines feeding individual residential bathroom faucets, toilets, and radiant heating floor loops.

Size Navigation

Compare Other PEX Tubing Sizes

Explore adjacent diameter calculations or compare with PVC & Copper piping.

Overview Directory Master Pipe Volume Calculator Next Size → 3/4" PEX Tubing
Expert FAQ Guide

1/2" PEX Tubing FAQs

Frequently asked engineering and volumetric capacity questions for 1/2" PEX.

2 Questions Answered
Q1 How many gallons of water in 100 ft of 1/2" PEX tubing?

A 100-foot coil of 1/2-inch SDR-9 PEX tubing holds approximately 0.92 US Gallons (3.48 Liters) of water.

Q2 Why does 1/2" PEX hold less water than 1/2" Copper?

Because PEX has a thicker wall (0.075" vs 0.040" for Type L Copper), its inside diameter is 0.475" compared to 0.545" in copper, holding about 24% less volume per foot.

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