Pressure, flow rate, buoyancy, viscosity, and hydraulic calculators. Browse our free fluid mechanics tools below — all calculators are instant, accurate, and require no sign-up.
Air Pressure at Altitude Calculator — Calculate atmospheric pressure, temperature, and air density at any altitude using the International Standard Atmosphere (ISA) model. Supports humidity correction.
Cv Flow Calculator — Calculate liquid flow rate, required Cv, or pressure drop using Q = Cv√(ΔP/SG). Quick Cv sizing for valves, fittings, and regulators.
BMEP Calculator (Brake Mean Effective Pressure) — Calculate brake mean effective pressure from power, displacement, and RPM. Compare engine efficiency across sizes. Supports kW, hp, 2-stroke and 4-stroke.
Darcy's Law Calculator — Calculate groundwater flow using Darcy's law Q = KiA. Compute Darcy velocity, seepage velocity, travel time, and total flow for any soil type.
Darcy–Weisbach Calculator — Calculate pipe friction head loss and pressure drop with the Darcy–Weisbach equation. Uses the Colebrook–White equation for turbulent friction factor.
Differential Pressure Calculator — Calculate flow rate from differential pressure across orifice plates, Venturi tubes, flow nozzles, and Pitot tubes. Converts ΔP to flow velocity and volume.
Hydraulic Conductivity Calculator — Calculate hydraulic conductivity K, Darcy velocity, seepage velocity, and total flow for soils and aquifers. Presets for gravel through clay.
Hydraulic Jump Calculator — Calculate downstream depth, energy loss, jump length, and power dissipated in a hydraulic jump. Supports rectangular, trapezoidal, and triangular channels.
Hydraulic Gradient Calculator — Calculate hydraulic gradient i = Δh/L from head drop and flow path length. Supports elevation + pressure mode, slope-angle conversion, and scenario presets.
Hydraulic Pressure Calculator — Calculate hydraulic cylinder force, speed, and power from pressure, bore, rod, and flow rate. Supports extend and retract calculations.
Hydraulic Radius Calculator — Calculate hydraulic radius Rh = A/P and hydraulic diameter Dh = 4A/P for circular, rectangular, trapezoidal, and triangular cross-sections.
Hydrostatic Pressure Calculator — Calculate pressure at depth P = P₀ + ρgh for any liquid. Converts to kPa, atm, psi, bar, and mmHg with force on surfaces.
Isentropic Flow Calculator — Calculate isentropic flow relations: T/T₀, P/P₀, ρ/ρ₀, A/A*, velocity, and normal-shock properties for any Mach number and gas.
Manometer Calculator — Calculate pressure from manometer height difference for U-tube, differential, inclined, and well-type manometers with multiple manometer fluids.
Kinematic Viscosity of Air Calculator — Calculate kinematic viscosity ν, dynamic viscosity μ, and density of air at any temperature and pressure using Sutherland's law.
Open Channel Flow Calculator (Manning) — Calculate flow rate, velocity, and Froude number in open channels using Manning's equation. Supports rectangular, trapezoidal, triangular, and circular shapes.
Orifice Flow Calculator — Calculate flow rate through an orifice using Q = CdA√(2gh). Supports sharp-edged, beveled, and rounded orifice types with multiple fluids.
Pipe Flow Calculator — Calculate velocity, Reynolds number, friction factor, head loss, and pressure drop for pipe flow. Includes elevation change and pumping power.
Reynolds Number Calculator — Calculate the Reynolds number Re = ρVD/μ to classify pipe or external flow as laminar, transitional, or turbulent. Includes friction factor and entrance length.
Radiation Pressure Calculator — Calculate radiation pressure, force, and acceleration from electromagnetic radiation on absorbing or reflecting surfaces. Solar sail and laser propulsion analysis.
Valve Flow Coefficient (Cv / Kv) Calculator — Calculate valve Cv, flow rate, or pressure drop for control valves. Convert between Cv (US) and Kv (metric) with specific-gravity correction.
Water Viscosity Calculator — Calculate dynamic viscosity, kinematic viscosity, density, and thermal properties of water at any temperature from 0–100 °C.