EngineeringFormulaIf you know area and velocity
Start with Flow Rate or Continuity Equation. These are the cleanest tools when the flow is already measured or when you are moving between two pipe or duct sections.
Fluid Mechanics
One area-velocity relationship, applied to pipes, ducts, and open discharge.
Liquids and gases in motion get treated as one continuous discipline here, which is why a duct-airflow tool like CFM sits alongside a liquid-hydraulics tool like Pump Hydraulic Power - both come from the same area-velocity relationship at their core. Flow Rate and Continuity Equation cover that relationship directly; Bernoulli Equation extends it to pressure and elevation changes along a streamline; Reynolds Number classifies the flow regime those equations assume.
Hydrostatic Pressure, Buoyant Force, and Orifice Flow round out the discipline with fluids at rest or discharging through an opening rather than moving through a closed section. Every calculator here models a single, named textbook relationship - none of them are a general-purpose pressure-loss or pipe-network solver.
Fluid Mechanics Calculators
18 tools- Reynolds Number CalculatorRe = ρ v D / μ
- Bernoulli Equation Calculatorp1 = p2 + 1/2 ρ (v2² - v1²) + ρ g (z2 - z1)
- Hydrostatic Pressure Calculatorp = ρ g h
- Buoyant Force CalculatorF_B = rho g V_d
- Pump Hydraulic Power CalculatorP_h = rho g Q H
- Orifice Flow CalculatorQ = C_d A √(2 Delta p / rho)
- Venturi CalculatorQ = Cd A2 sqrt(2 Delta p / (rho (1 - beta^4)))
- Continuity Equation CalculatorA1 = A2 v2 / v1
- Flow Rate CalculatorQ = A v
- CFM CalculatorCFM = (W × H) v
- Duct Size CalculatorA = Q / v
- Pipe Size CalculatorA = Q / v
- Manning Equation CalculatorA = b × y
- Static Pressure CalculatorTESP = |Ps| + |Pr|
- Air Changes per Hour CalculatorV = L x W x H
- Water Pressure CalculatorP = ρ g h
- Pipe Volume CalculatorV = π d² L / 4
- Pressure Drop CalculatorΔp = f (L/D) (ρv²/2) + K (ρv²/2) + ρ g Δz
Which calculator should I start with?
If pressure, elevation, or head is driving the result
Use Bernoulli Equation, Orifice Flow, Hydrostatic Pressure, or Pump Hydraulic Power depending on whether you are balancing streamline energy, an opening, a static liquid column, or a pump duty point.
If air distribution is the real problem
Use CFM, Duct Size, Static Pressure, and Air Changes per Hour together. Airflow volume, duct velocity, pressure loss, and room ventilation rate are linked, so one number rarely tells the whole story.
Browse all disciplines or the full calculator index.