Hydraulic Power Calculator

Calculator

Formula used

How to use this calculator

1. Select Pressure × Flow if you know Δp across the system.
2. Select Head × Flow if you work with lift or TDH.
3. Enter flow rate and choose units that match your data.
4. Pick a fluid preset, or set a custom density value.
5. Add pump and motor efficiencies to estimate input power.
6. Optional: include loss allowance for piping and restrictions.
7. Optional: add runtime and energy rate for cost projections.
8. Press Calculate, then download CSV or PDF if needed.

Hydraulic power from measured pressure and flow

Hydraulic power is computed as the product of pressure differential and volumetric flow. The calculator converts entered units to SI, then reports watts, kilowatts, horsepower, and BTU/hr. As a reference, 120 bar with 30 L/min produces about 6.0 kW of hydraulic output before efficiency adjustments. This method suits actuators, presses, and power packs where operating pressure is measured at the manifold.

Head-based modeling for pumping applications

When head is known instead of pressure, the calculator uses P = ρ·g·Q·H and also returns an equivalent pressure. With fresh water near 998 kg/m³ and g = 9.80665 m/s², 10 m head is roughly 0.98 bar. A loop at 18 m head and 0.02 m³/s yields about 3.5 kW hydraulic power. This approach aligns with vendor head curves and TDH calculations.

Efficiency stacking and motor sizing

Results are split into hydraulic output, required shaft power, and electrical input. Pump efficiency converts hydraulic power to shaft power, and motor efficiency converts shaft power to electrical input. Overall efficiency equals η_pump×η_motor. For η_pump=80% and η_motor=90%, overall efficiency is 72%, so input power is output divided by 0.72. This supports motor kW selection and thermal margin checks.

Loss allowances for piping, valves, and filtration

Real systems include line losses from fittings, control valves, filters, and elevation changes. The loss allowance increases Δp or head by a selected percentage to model uncertain restrictions without rebuilding the full network. A 10% allowance multiplies effective Δp or H by 1.10, increasing hydraulic power by the same factor at constant flow. Use measured drops when available, and reserve larger allowances for early design.

Energy, cost, and reporting workflows

Operating cost is estimated by multiplying electrical input kW by runtime hours per day to compute kWh, then scaling to 30-day and annual totals. With 8.5 kW input and 4 h/day, daily energy is about 34 kWh. At a rate of 0.18 per kWh, cost is about 6.12 per day. CSV export fits spreadsheets, while the PDF snapshot supports maintenance logs, commissioning packs, and approvals. Use consistent units to compare sites, seasons, and operating points accurately today.

FAQs

1) What does hydraulic power represent?

It is the useful power carried by the fluid, calculated from pressure and flow, or from head and flow. It excludes pump and motor losses, so it is always lower than required electrical input.

2) Should I use pressure or head as input?

Use pressure when Δp is measured across the pump, valve, or actuator. Use head when you have TDH or lift data from pump curves. The calculator converts between head and pressure using density and gravity.

3) Why is electrical input higher than hydraulic output?

Input includes conversion losses. The calculator divides hydraulic power by pump efficiency to get shaft power, then divides again by motor efficiency to estimate electrical input. Lower efficiencies or added losses increase the gap.

4) How do I pick the right fluid density?

Select a preset for water, sea water, or hydraulic oil when conditions are typical. Use custom density when temperature, concentration, or oil grade differs. Density mainly affects head-to-pressure conversion and head-based power.

5) What is the loss allowance used for?

It increases effective Δp or head to represent piping, fittings, filters, and control valve losses. Use small percentages for minor uncertainty, and replace allowances with measured or calculated losses during detailed design.

6) How reliable are the energy and cost numbers?

They are planning estimates based on runtime and a single energy rate. For higher accuracy, use logged operating hours, demand charges if applicable, and measured efficiencies at the actual operating point.

Example data table