Flow Rate Calculator

Calculate volume flow rate Q, velocity, mass flow for pipe, rectangular channel and orifice plate. Instant unit conversion (m³/h, GPM, L/s, kg/s).

Volume Flow Rate Q

120 m³/h

Pipe D=150mm, v=2 m/s

Flow Rate & Velocity

Featured: Pipe • Channel • Orifice • Units Conversion

Calculation Type

Geometry

Pipe Diameter D (mm)

Velocity v (m/s)

Density ρ (kg/m³) - for mass flow

Common conversions

Q = v × A
Pipe: A = π D²/4
Channel: A = b × h
Orifice: Q = Cd × A_orifice × √(2 ΔP / ρ (1-β⁴))

Enter parameters to calculate flow rate

Water pipes: 1–3 m/s

Air ducts: 5–10 m/s

Pumped liquids: 1.5–2.5 m/s

1 m³/h = 4.403 GPM = 0.278 L/s

1 CFS = 448.8 GPM

Mass flow = Q × ρ