Standard 3/4" SDR-9 PEX tubing has an inner diameter of 0.671 inches, holding 0.0184 US gallons (0.228 liters per meter) per linear foot. Part of our universal Pipe Volume Calculator and Water Pipe Volume tools.
Calculations are based on cylindrical formula \(V = \pi r^2 L\). Verify dimensions against manufacturer specs for code submittals.
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 | 0.018 gal | 0.07 L | 0.002 ft³ | 0.2 lbs | 0.1 lbs | 0.3 lbs |
| 5 ft | 0.092 gal | 0.35 L | 0.012 ft³ | 0.8 lbs | 0.5 lbs | 1.3 lbs |
| 10 ft | 0.184 gal | 0.69 L | 0.025 ft³ | 1.5 lbs | 1.0 lbs | 2.5 lbs |
| 25 ft | 0.460 gal | 1.74 L | 0.061 ft³ | 3.8 lbs | 2.5 lbs | 6.4 lbs |
| 50 ft | 0.92 gal | 3.5 L | 0.12 ft³ | 7.6 lbs | 5.1 lbs | 12.8 lbs |
| 100 ft | 1.84 gal | 6.9 L | 0.25 ft³ | 15.3 lbs | 10.2 lbs | 25.5 lbs |
| 200 ft | 3.68 gal | 13.9 L | 0.49 ft³ | 30.6 lbs | 20.4 lbs | 51.0 lbs |
| 300 ft | 5.52 gal | 20.8 L | 0.74 ft³ | 45.9 lbs | 30.6 lbs | 76.5 lbs |
| 500 ft | 9.20 gal | 34.7 L | 1.23 ft³ | 76.5 lbs | 51.0 lbs | 127.5 lbs |
| 1000 ft | 18.40 gal | 69.5 L | 2.46 ft³ | 153.0 lbs | 102.0 lbs | 255.0 lbs |
Step-by-step mathematical demonstration using cylinder geometric principles and SDR-9 ASTM specifications.
Nominal size is 3/4", but true inner diameter is 0.671 inches.
r = ID / 2 = 0.671 / 2 = 0.3355" Compute circular cross-section area using $A = \pi \times r^2$:
A = \pi \times (0.3355)^2 = 0.3536 sq in Multiply cross-sectional area by 12 inches (1 linear foot):
V_linear = 0.3536 \times 12 = 4.243 cu in/ft Divide cubic inches by 231 (cubic inches in 1 US Gallon):
Gallons/Ft = 4.243 / 231 = 0.0184 Gal/Ft Physical dimensions, pressure thresholds, and hydraulic velocity limits.
Primary Use Case: Ideal for main supply trunks feeding multiple 1/2" PEX branches, water softeners, and continuous water heater connections.
Explore adjacent diameter calculations or compare with PVC & Copper piping.
Frequently asked engineering and volumetric capacity questions for 3/4" PEX.
A 300-foot continuous run of 3/4-inch PEX holds 5.52 US Gallons (20.9 Liters) of water.