Fluid Calculator

  • Absolute to Gauge Pressure Calculator
    Convert absolute pressure to gauge pressure instantly. Enter absolute and atmospheric pressure to find gauge pressure using Pg = Pabs − Patm.
  • Water Vapor Pressure Calculator
    Calculate the saturation vapor pressure of water at any temperature using the Tetens formula. Get results in kPa, hPa (mbar), and mmHg.
  • Hoop Stress Calculator (Thin-Wall Pipe)
    Calculate hoop (circumferential) and axial stress in a thin-wall pressurized pipe or cylinder using σ = PD/2t. Enter pressure, diameter and wall thickness.
  • Pipe Wall Thickness Calculator (Barlow's Formula)
    Calculate minimum pipe wall thickness from internal pressure, outside diameter, and allowable stress using Barlow formula t = PD/(2S). In inches and mm.
  • Sprinkler Flow Rate Calculator
    Calculate fire sprinkler discharge flow rate (GPM) from K-factor and pressure using Q = K times the square root of P. Free hydraulic calculator.
  • Air Flow Rate (CFM) Calculator
    Calculate airflow in CFM from air velocity (ft/min) and rectangular duct dimensions. Uses CFM = velocity × duct area for HVAC sizing.
  • Pipe Water Velocity Calculator (GPM & Diameter)
    Calculate water velocity (ft/s) in a pipe from flow rate in GPM and inside diameter in inches. Fast, accurate plumbing and pipe-sizing tool.
  • Water Column to Pressure Calculator
    Convert a water column height (feet or inches of water) into pressure in PSI, kPa and bar. Uses ftH2O x 0.4335 and inH2O x 0.03613.
  • Wind Load Pressure Calculator
    Calculate dynamic wind pressure with q = ½ρv². Enter wind speed and air density to get pressure in pascals, plus total wind force on an area.
  • Flow Rate to Velocity Converter
    Convert volumetric flow rate (Q) and pipe diameter into fluid velocity. Supports m³/s, L/s, GPM and mm, cm, in. Free pipe flow velocity calculator.
  • Darcy-Weisbach Pressure Drop Calculator
    Calculate pressure drop in a pipe using the Darcy-Weisbach equation from friction factor, length, diameter, density and velocity. Get Pa, kPa, bar and head loss.
  • Water Flow from Pipe Pressure & Diameter Calculator
    Estimate water flow rate from pipe pressure and inner diameter using Q = A·√(2P/ρ). Get results in L/min, m³/s, m³/h plus flow velocity.
  • Pump Power (HP) Calculator
    Calculate pump brake horsepower (BHP) and water horsepower from flow rate (GPM), total head (ft), specific gravity, and pump efficiency.
  • Mixing Two Fluids Final Temperature Calculator
    Calculate the final equilibrium temperature when two fluids are mixed, using mass, specific heat, and starting temperatures. Free physics tool.
  • Valve Kv Flow Coefficient Calculator
    Calculate the valve flow coefficient Kv (metric) from flow rate, specific gravity and pressure drop. Get equivalent Cv too. Free engineering tool.
  • SCFM to ACFM Calculator
    Convert SCFM to ACFM using actual pressure and temperature. Free airflow conversion calculator for compressors, blowers, and HVAC systems.
  • Head Loss per 100 ft Calculator (Hazen-Williams)
    Calculate Hazen-Williams friction head loss in feet of water per 100 ft of pipe from flow rate (gpm), inside diameter, and C coefficient. US units.
  • Pump Hydraulic Power (kW) Calculator
    Calculate pump hydraulic power in kW from fluid density, gravity, flow rate and head using P = ρgQH. Also outputs watts, horsepower and shaft power.
  • 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.
  • Water Flow Rate Through a Hose Calculator
    Estimate water flow rate through a hose from inner diameter, supply pressure and discharge coefficient. Get liters/min, GPM and exit velocity instantly.
  • 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.

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