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Water flow rate calculator

Flow in gallons or liters per minute, from a pipe size and water speed, or from timing a bucket fill.

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US gallons per minute 6.88 gpm

How it works

Q = π × (d ÷ 2)² × v

Flow is how much water passes in a given time. In a pipe it’s the pipe’s inside cross-section (π × radius²) times how fast the water moves. The simplest real-world check is the bucket test: time how long a bucket of known size takes to fill and divide the volume by the time.

  1. Pipe cross-section × speed 3.14159265 × (0.01905 ÷ 2)² × 1.524 = 0.000434 m³/s
  2. Per minute, in liters 0.000434 × 60,000 = 26.06 L/min

Printed from rocketcalc.io/geometry/water-flow