Enter your Flow Rate and Pipe Diameter (with your choice of units for each) into the Water Velocity Calculator, and it'll work out the Water Velocity in both metric and imperial, plus the Pipe Cross-Sectional Area and a Velocity Status telling you whether your flow is within a healthy range.
Water Velocity
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Water Velocity (Metric)
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Pipe Cross-Sectional Area
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Velocity Status
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Water velocity is the speed at which water flows through a pipe, typically measured in feet per second or meters per second. It's crucial for proper pipe sizing, preventing erosion, and ensuring efficient water distribution systems.
For most applications, water velocity should be between 3-8 feet per second. Velocities below 3 ft/s may cause sediment buildup, while velocities above 8 ft/s can cause pipe erosion and excessive pressure loss.
Water velocity is calculated using the formula: V = Q / A, where V is velocity, Q is flow rate, and A is the pipe's cross-sectional area. The area is calculated as π × (diameter/2)².
This calculator supports multiple units: flow rate in GPM, CFS, LPS, acre-inches/day, or acre-feet/day; pipe diameter in inches, feet, millimeters, centimeters, or meters.
Excessive water velocity can cause pipe erosion, increased pressure loss, water hammer, noise, and premature system failure. It's recommended to keep velocity under 8 ft/s for most applications.
Low water velocity (under 3 ft/s) can lead to sediment accumulation, reduced system efficiency, stagnant water conditions, and potential water quality issues in distribution systems.
Water velocity is inversely related to pipe diameter squared. Doubling the pipe diameter reduces velocity by approximately 75%, assuming constant flow rate. Larger pipes allow for slower, more efficient flow.