Free Hydraulic Calculator

A range of powerful hydraulic calculators for all fluid power systems

Calculate hydraulic power unit performance, efficiency, pipework size, thermal balance and accumulators capacities.
Also available as a hydraulic calculator mobile phone app here.

Fluid power, pump, system and pipework calculations

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Hydraulic pump input and output power calculator

1 Set the pump speed and displacement or output flow.

2 Set the load pressure by controlling the load on the motor

3 Typical input power, flow, shaft torque, and output power calculations are shown at the bottom of the screen.

Hydraulic pipeline velocity calculator

It's vital that hydraulic pressure, return and suction pipes are sized correctly.

Every system is slightly different and the lower the pressure difference the less energy you waste, however, the range of acceptable figures used are based on generally accepted industrial standards.

1 Set the pump flow rate

2 Set the suction, pressure and return pipes inside diameter.

3 The pipe fluid velocities are shown in blue if they are acceptable and red if they are too fast.

4. The vertical guages flash if the flow is borderline or too fast.

Reservoir temperature stability calculations

Check whether your power unit reservoir will maintain a stable temperature or overheat.

1. Set the input power e.g. the hydraulic power losses converted into heat by the hydraulic system. You know the input power so deduct the work done and assume the rest goes into heating the fluid.

2. Enter the ambient temperature and reservoir volume, the surface area is approximated from the volume.

3. Set the temperature of the fluid in the tank. The heat radiated from the reservoir will depend on the temperature of the fluid.

4. Set the input power from the electric heater.

5. The offline cooler requires the flow of fluid, water temperature difference and water flow to be set.

6. Look at the tank temperature rise rate and calculations to see whether your reservoir temperature can be controlled.

In the hydraulic systems section, there is a real time simulation of a power unit. With that calculator, you can set your reservoir conditions and leave the program running to see where the final reservoir temperature stops.

Accumulator precharge pressure calculations

1. Set the gas precharge pressure.

2. Set the minimum and maximum working pressure.

3. Set the nominal accumulator volume.

4. The usable volume of the accumulator will be shown below.

Pneumatic air flow calculations

1. Enter the upstream and downstream pressures.

2. Enter the conductance and critical pressure ratios.

3. The Flow of Free Air calculation is shown at the bottom of the calculator.


Every attempt has been made to ensure these calculations are accurate. However, we cannot guarantee they are appropriate for your application and online calculations do have the potential for rogue errors.

Please inform us if you find any errors and do not really on these results without double checking figures using manual calculations.