What Is the Equation for Flow Rate

Flow Rate Formula:

\[ Q = V \times A \times 448.83 \]

Flow Rate (Q): GPM

Definition: This calculator determines the volumetric flow rate (Q) in gallons per minute (GPM) based on fluid velocity and cross-sectional area.

Purpose: Essential for hydraulic engineers, plumbers, and fluid system designers to size pipes and pumps correctly.

The calculator uses the formula:

\[ Q = V \times A \times 448.83 \]

Where:

Explanation: The velocity multiplied by area gives flow in ft³/s, which is then converted to GPM.

Details: Accurate flow rate calculations ensure proper system design, prevent pipe erosion, and maintain desired pressure levels.

Tips: Enter the fluid velocity in ft/s and cross-sectional area in ft². For circular pipes, area = π × (diameter/2)².

Q1: Why 448.83 as the conversion factor?
A: It converts cubic feet per second to gallons per minute (1 ft³/s = 448.83 GPM).

Q2: What's a typical velocity for water in pipes?
A: 2-5 ft/s for supply lines, 5-10 ft/s for drainage to prevent sedimentation.

Q3: How do I calculate area for non-circular pipes?
A: Use appropriate geometry formulas (rectangle: width × height, etc.).

Q4: Does this work for gases?
A: Yes, but gas flow calculations often include additional factors like compressibility.

Q5: What if I know diameter instead of area?
A: First calculate area using A = π × r² (r = diameter/2).