GPM Flow Rate Calculator
Calculate flow rate using multiple methods
Bucket/Container Test Method
Measure how long it takes to fill a known container.
Flow Rate
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Gallons per Hour
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Liters per Minute
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Pipe Velocity Method
Calculate GPM from pipe diameter and flow velocity.
Flow Rate
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Pipe Area
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Velocity Guidelines:
• Water supply: 4-8 ft/sec recommended
• Drain lines: 2-4 ft/sec minimum self-cleaning
• Water supply: 4-8 ft/sec recommended
• Drain lines: 2-4 ft/sec minimum self-cleaning
Orifice Flow Method
Calculate flow through an orifice or nozzle.
Flow Rate
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Orifice Area
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Flow Rate Conversions
1 GPM =
60 GPH
3.785 LPM
0.134 CFM
Flow Formula
Q = A × V
GPM = 2.449 × d² × V
(d in inches, V in ft/s)
Orifice Formula
Q = Cd × A × √(2gh)
GPM = 29.84 × Cd × d² × √P
(P in PSI)