Pipe Volume Calculator
Whether you are draining a plumbing system, sizing a water supply, or estimating irrigation capacity, knowing the volume of water inside a pipe is essential. Enter the pipe's inner diameter and length to calculate the total volume in gallons, liters, and cubic feet, plus the weight of the water.
The volume of a pipe is calculated using the cylinder formula: V = π x (diameter/2)² x length. The result in cubic inches is then converted to gallons by dividing by 231 (the number of cubic inches in a US gallon).
Use the inner diameter (ID) of the pipe, not the outer diameter (OD). The nominal pipe size (e.g., "1-inch pipe") doesn't match the actual inner diameter. For example, a 1-inch Schedule 40 PVC pipe has an actual ID of 1.029 inches. Check the manufacturer's specifications for exact ID values.
Water weighs 8.34 pounds per gallon at room temperature. This weight is important for structural support calculations. A 100-foot run of 4-inch pipe holds over 40 gallons, weighing more than 340 pounds. Always account for water weight when routing pipes through ceilings or along walls.