Fluid Calculator

  • Surface Tension Calculator
    Calculate surface tension (γ) from the force on a wire and its wetted length using γ = F / (2L). Free physics calculator with mN/m output.
  • Immersed (Apparent) Weight Calculator
    Calculate the immersed or apparent weight of an object in a fluid using buoyancy. Enter mass, volume, fluid density and gravity to get apparent weight in newtons.
  • Swamee-Jain Friction Factor Calculator
    Calculate the Darcy friction factor for turbulent pipe flow using the Swamee-Jain explicit equation from roughness, diameter, and Reynolds number.
  • NPSH Available Calculator
    Calculate Net Positive Suction Head available (NPSHa) for centrifugal pumps to avoid cavitation, using surface pressure, vapor pressure, density and head losses.
  • IV Drip Rate Calculator
    Calculate IV infusion drip rate in drops per minute and seconds per drop from fluid volume, infusion time or hourly rate, and the drop-set factor (20 or 60 gtt/mL).
  • Volumetric Flow Rate Conversion Calculator
    Convert volumetric flow rate between 21 units (L/min, m3/h, CFM, US/UK GPM, mL/s and more) instantly. Free, accurate SI-based flow rate converter.
  • Kinematic Viscosity of Air Calculator
    Calculate the kinematic viscosity of air (ν = μ / ρ) from dynamic viscosity and air density. Get results in m²/s and centistokes instantly.
  • y+ Calculator
    Calculate y+ (dimensionless wall distance) for CFD meshing from density, viscosity, wall shear stress and first cell distance. Includes friction velocity.
  • Water Pressure at Depth Calculator
    Calculate hydrostatic water pressure at any depth using P = P_atm + ρgh. Get absolute and gauge pressure in Pa, kPa and atmospheres instantly.
  • Stokes' Law Calculator
    Calculate the terminal settling velocity of a spherical particle in a fluid using Stokes' Law from density, radius, viscosity and gravity.
  • Prandtl-Meyer Expansion Calculator
    Compute the Prandtl-Meyer function ν(M) for supersonic expansion flow from Mach number and specific heat ratio γ, with the Mach angle output.
  • Prandtl Number Calculator
    Calculate the Prandtl number (Pr) from specific heat, dynamic viscosity, and thermal conductivity. Free dimensionless heat-transfer calculator with worked example.
  • Pounds per Minute Calculator
    Calculate mass flow rate in pounds per minute (lb/min) by dividing total mass in pounds by elapsed time in minutes. Fast, free, and accurate.
  • Poiseuille's Law Calculator
    Calculate the volumetric flow rate of a viscous fluid through a cylindrical pipe using Poiseuille's Law from pressure, radius, viscosity, and length.
  • Pipe Flow Calculator
    Calculate the volumetric flow rate of a fluid through a round pipe from its inner diameter and velocity using Q = (π/4)·d²·v. Results in m³/s, L/s and m³/h.
  • Pipe Velocity Calculator
    Calculate fluid velocity inside a pipe from flow rate and inside diameter. Supports m³/s, m³/h, L/s and L/min with instant results.
  • Manometer Pressure Calculator
    Calculate manometer pressure from fluid column height using P = ρgh. Get results in Pa, kPa, bar, mmHg, and psi instantly.
  • Mach Number Calculator
    Calculate Mach number from object speed and speed of sound using M = v/a. Get the Mach value and flow regime (subsonic, supersonic, hypersonic).
  • Knudsen Number Calculator
    Calculate the Knudsen number (Kn = λ / L) from mean free path and characteristic length, and identify the flow regime: continuum, slip, transitional, or free molecular.
  • Hydrostatic Pressure Calculator
    Calculate hydrostatic pressure with P = ρgh from fluid density, gravity, and depth. Get results in Pa, kPa, bar, and atmospheres instantly.
  • Hydraulic Radius Calculator
    Calculate hydraulic radius (Rh) from cross-sectional area and wetted perimeter using Rh = A / P. Free, instant open-channel flow calculator.
  • Hydraulic Pressure Calculator
    Calculate hydraulic pressure from force and piston area using P = F / A. Get results in pascals, kPa, bar, and psi instantly.
  • Pitot Tube Velocity Calculator
    Calculate fluid or airspeed velocity from a pitot tube's differential pressure and density using v = √(2ΔP/ρ). Free, instant results in m/s, km/h, mph.
  • Buoyant Force Calculator
    Calculate buoyant (upthrust) force using Archimedes' principle: F = ρ·V·g. Enter fluid density, displaced volume and gravity to get the force in newtons.

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