Fluid Calculator

  • Pump Brake Power & Efficiency Calculator
    Calculate pump brake (shaft) power from fluid density, flow rate, head and efficiency using P = ρgQH/η. Get kW and hp output instantly.
  • Pressure Drop from Flow Rate Calculator
    Calculate pipe pressure drop with the Darcy-Weisbach equation from friction factor, length, diameter, fluid density, and velocity. Get results in Pa, kPa, and bar.
  • Time to Fill Tank Calculator
    Calculate how long it takes to fill a tank from its volume and water flow rate using t = V / Q. Supports liters, gallons, m3, and multiple flow units.
  • Gas Density Calculator
    Calculate the density of an ideal gas from pressure, molar mass, and temperature using ρ = PM/(RT). Free, instant results in kg/m³ and g/L.
  • Reynolds Number for Pipe Flow Calculator
    Calculate the Reynolds number for fluid flow in a pipe from density, velocity, diameter and viscosity. Re = ρvD/μ. Find if flow is laminar or turbulent.
  • Hydrostatic Pressure Calculator
    Calculate hydrostatic (fluid) pressure with P = ρgh. Get gauge and absolute pressure in Pa, kPa, bar and atm from density, gravity and depth.
  • Water Hammer Pressure Surge Calculator
    Calculate water hammer pressure surge with the Joukowsky equation. Enter fluid density, pressure wave speed and velocity change to get the surge in Pa, kPa, bar and psi.
  • Hydraulic Press Force Calculator
    Calculate hydraulic press output force using Pascal's law. Enter input force and both piston areas to find F2 = F1 × (A2/A1) plus system pressure.
  • Continuity Equation Flow Rate Calculator
    Calculate volumetric flow rate Q = A·v and downstream velocity using the continuity equation A₁v₁ = A₂v₂ for circular pipes. Free and instant.
  • Pipe Flow Velocity Calculator
    Calculate fluid velocity in a pipe from flow rate and inner diameter using v = Q / (π/4 × D²). Free, instant pipe flow speed calculator.
  • Rectangular Pool Gallons Calculator
    Calculate how many gallons of water your rectangular swimming pool holds using length, width, and average depth. Free, instant pool volume calculator.
  • Water Tank Capacity Calculator
    Calculate water tank capacity in liters for rectangular or cylindrical tanks. Enter dimensions in meters to get volume, liters and US gallons instantly.
  • Bucket Volume Calculator
    Calculate the volume of a tapered bucket from its top diameter, bottom diameter and height. Get results in liters, US gallons and UK gallons instantly.
  • Hot Tub Volume Calculator
    Calculate how many gallons of water your hot tub holds. Enter the shape and dimensions to estimate volume in gallons, liters and cubic feet.
  • Horizontal Cylindrical Tank Volume Calculator
    Calculate the liquid volume in a horizontal cylindrical tank for any fill height. Get partial-fill volume, fill %, liters and US gallons instantly.
  • Oval (Stadium) Tank Volume Calculator
    Calculate the volume of an oval (stadium / capsule cross-section) tank from its width, height and length. Get liters, cm³ and US gallons instantly.
  • Pounds to Gallons Calculator (Water)
    Convert pounds of water to US gallons instantly. Enter the weight in pounds and get the volume using the standard 8.34 lb per gallon factor.
  • Head to Pressure Calculator
    Convert pump head (meters or feet) to pressure in PSI, kPa, bar and Pascals using P = ρgH. Supports any fluid specific gravity.
  • Mass Flow Rate Calculator
    Calculate mass flow rate (ṁ = ρAV) from fluid density, cross-sectional area, and flow velocity. Get kg/s and volumetric flow rate instantly.
  • Fluid Density Calculator
    Calculate fluid density from mass and volume using ρ = m / V. Get results in kg/m³ and g/cm³ instantly with this free density calculator.
  • Pump Power / Hydraulic Power Calculator
    Calculate pump shaft power and hydraulic power from flow rate, head, fluid density, gravity and efficiency. Get results in kW and HP instantly.
  • Manning's Equation Open Channel Flow Calculator
    Calculate open channel flow velocity and discharge with Manning's equation using roughness, area, wetted perimeter, and slope (SI units, m³/s).
  • Capillary Rise Calculator
    Calculate capillary rise height in a thin tube using Jurin's Law from surface tension, contact angle, liquid density, tube radius and gravity.
  • Cups to Milliliters Converter
    Convert US cups to milliliters (mL) instantly. Uses the exact factor 1 cup = 236.5882365 mL for accurate cooking and recipe measurements.

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