How to Calculate Pipe Volume in Gallons per Foot
To calculate liquid volume held in a cylindrical pipe run:
- Determine Inner Diameter ($ID$): Measure or look up the inner diameter in inches (for example, Schedule 40 PVC 12-inch pipe has an actual $ID$ of 11.938 inches).
- Calculate Radius ($r$): $r = ID / 2$ in inches.
- Calculate Volume in Cubic Inches: $V = \pi \times r^2 \times (L \times 12)$ where $L$ is length in feet.
- Convert to US Gallons: Divide cubic inches by 231: $\text{Gallons} = V \div 231$.
For bulk water storage vessels or system reservoirs, connect this pipeline volume with our Tank Volume Calculator.
Standard Pipe Volume Quick Reference (Gallons per Linear Foot)
Common nominal pipe sizes hold the following liquid volumes per 1 foot of length:
- 1/2″ Pipe: 0.010 Gallons / ft (0.085 lbs water/ft)
- 3/4″ Pipe: 0.023 Gallons / ft (0.192 lbs water/ft)
- 1″ Pipe: 0.041 Gallons / ft (0.340 lbs water/ft)
- 2″ Pipe: 0.163 Gallons / ft (1.360 lbs water/ft)
- 4″ Pipe: 0.653 Gallons / ft (5.443 lbs water/ft)
- 6″ Pipe: 1.469 Gallons / ft (12.25 lbs water/ft)
- 12″ Pipe: 5.875 Gallons / ft (49.00 lbs water/ft)
