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How to use it
Units of measurement. Choose the quantity, type the value and select the source and target units; or search for a unit directly by symbol or name (for example "psi", "gauss" or "centistokes"). Below the result you'll find the same value expressed in all the units of the quantity, useful when comparing catalogues from different manufacturers.
Physical relations. Here the quantities are different but linked by a physical law: choose the relation and type the value you know in any field, and the others update. For example the wavelength of a light and the energy of its photons, the pressure and height of a water column, the power and torque of a motor at a given speed.
Available quantities
Geometry and time: length, area, volume, angle, time, frequency. Mechanics: mass, force, pressure and stress, torque, energy, power, speed, acceleration, angular velocity, momentum, angular momentum, mass and area moments of inertia, section modulus, stiffness, density. Fluids: volumetric and mass flow rate, dynamic and kinematic viscosity, fuel consumption. Heat: temperature and temperature differences, conductivity, heat transfer, specific heat, specific energy, heat flux, expansion, entropy. Electricity and magnetism: charge, voltage, current, resistance, conductance, capacitance, inductance, resistivity, electric field, magnetic flux density and field strength, magnetic flux. Radiation: activity, absorbed dose, equivalent dose, exposure. Other: illuminance, luminance, amount of substance, concentration, digital data.
Physical relations: electromagnetic wave and photon, oscillations and rotations, mass-energy equivalence, temperature and thermal energy with Wien's law, moles and particles, pressure and fluid column, sound level, decibels, power-torque-speed, mass and weight, kinetic energy, Lorentz factor, battery charge and energy.
The factors are the exact ones from the international definitions (inch = 25.4 mm, pound = 0.45359237 kg, standard gravity 9.80665 m/s²). Temperature is converted with a non-proportional relation, which is why temperature differences have their own quantity.
Units and technical drawings
When a project moves between European and American suppliers, conversion errors aren't in the numbers but in mixed-up units: kgf and kg, psi and psig, US and imperial gallons, metric and mechanical horsepower. If you need to convert a complete project or technical documentation, contact us for a consultation.
FAQ
What's the difference between CV (metric hp) and hp?
The metric horsepower (CV) is 735.5 W, the Anglo-Saxon mechanical horsepower (hp) 745.7 W. The difference is about 1.4%: a 100 kW motor is 136 CV or 134 hp.
Is one N/mm² equal to one MPa?
Yes: 1 N/mm² = 1 MPa = 10 bar. It's the unit normally used for material stresses and strengths.
What's the difference between dynamic and kinematic viscosity?
Kinematic viscosity (mm²/s or cSt) is the dynamic viscosity (mPa·s or cP) divided by the fluid density. Industrial oils are classified by kinematic viscosity at 40 °C (ISO VG grades).
Is a gallon the same everywhere?
No. The US gallon is 3.785 litres, the British imperial one 4.546 litres. In American pump and compressor catalogues, gpm normally refers to the US gallon.