Flow Rate Formula
Flow rate formulas, unit conversions and pipe velocity calculations for industrial use.
Basic Flow Rate Formula
Flow Rate (Q) = Velocity (v) × Cross-Sectional Area (A)
Q (m³/s) = v (m/s) × π × (D/2)²
From pipe diameter:
Q (LPM) = v (m/s) × π × (D_m / 2)² × 60,000
Flow Rate Unit Conversions
1 m³/hr = 16.667 LPM = 4.403 US GPM
1 GPM = 3.785 LPM = 0.227 m³/hr
1 L/s = 60 LPM = 3.6 m³/hr
1 CFM = 28.317 LPM = 1.699 m³/hr
Recommended Pipe Velocities
| Service | Recommended Velocity |
|---|---|
| Pump suction lines | 0.5 – 1.5 m/s |
| Pump discharge lines | 1.5 – 3.0 m/s |
| General water supply | 1.0 – 2.5 m/s |
| Above 3.5 m/s | Risk of erosion and water hammer |