Hydraulic Pressure Calculator

Hydraulic pressure needed for a cylinder force (bore-based)

This hydraulic pressure calculator is for one specific job: estimating the pressure required to generate a target cylinder force from a given cylinder bore diameter. This is the most common “shop-floor” sizing question when you are checking whether a hydraulic power pack, pump, valve setting, or hose rating is in the right ballpark for a cylinder-driven task such as pressing, lifting, clamping, or pushing.

You enter the force you want the cylinder to deliver and the cylinder bore diameter. The calculator converts that bore into piston area and then uses the standard relationship between force, pressure, and area. In plain terms: for a fixed bore, higher force needs higher pressure. For a fixed pressure, a larger bore delivers more force.

The result is shown in practical units (bar, MPa, and psi) because different datasheets and workshops use different conventions. The calculator also shows a few supporting figures that matter in real decisions: the piston area used in the calculation, and the “force per bar” you can expect for your bore at the efficiency you selected. That makes it easier to sanity-check the number without redoing the math or guessing if your result is off by a factor of ten.

How to use it: start with the default view. If you only know the force and bore, you will still get a valid pressure estimate. If you want a more conservative value, open the Advanced section and adjust efficiency and safety factor. Efficiency reduces the effective force you get from a given pressure because real systems have losses (seal friction, mechanical linkages, pressure drops, and imperfect conditions). A safety factor increases the required pressure so you have margin for variability such as uneven loading, transient spikes, or wear.

Interpreting the output: the “required pressure” is the pressure you would need at the cylinder to achieve the target force under the assumptions selected. If you are comparing this to a pump or relief valve spec, remember that system pressure measured at the pump can be higher than cylinder pressure due to line losses, or lower if there are restrictions. The calculator’s number is a sizing estimate, not a commissioning measurement.

This page is intentionally locked to the bore-based force-to-pressure relationship for a cylinder. It does not attempt to size pump flow, cycle time, hydraulic power, fluid heating, or hose velocity. Those are separate problems with different inputs and failure modes.

Assumptions and how to use this calculator

• Force input is force: Enter the force you need at the cylinder in kN. If you only have a mass, convert it to force first (mass × 9.81 gives Newtons, then divide by 1,000 for kN).
• Bore-based area: The calculator uses the full piston (bore) area, which corresponds to the cylinder extend side. It does not model rod-side (annulus) area or different pressures for retract.
• Efficiency is overall: The efficiency percentage is a single “all-in” factor for losses. If you do not know it, 85% is a common practical default for rough sizing.
• Safety factor is applied to pressure: The safety factor increases the required pressure after efficiency is considered. Use this when you want margin for variability, shock loads, or uncertainty.
• Steady load assumption: The calculation assumes a steady force requirement. Dynamic impacts, stick-slip, and shock loading can require higher pressure than a static calculation suggests.

Common questions

What formula does this calculator use?

It uses the standard relationship Pressure = Force ÷ Area, with optional adjustments. Bore diameter is converted into piston area, and then the force is divided by that area. If you include efficiency, the force is treated as “delivered force,” so the required hydraulic force is increased by dividing by efficiency. If you include a safety factor, the result is increased by that percentage.

Which pressure unit should I trust: bar, MPa, or psi?

They are the same pressure expressed in different units. Many hydraulic component datasheets use bar or MPa, while some regions and older equipment use psi. Use whichever matches the equipment you are checking. If your workshop language is bar, focus on bar and treat MPa and psi as convenience conversions.

Why does changing bore diameter move the pressure so much?

Because cylinder area depends on the square of diameter. A small increase in bore makes a meaningful difference in area, which reduces required pressure for the same force. If your output seems extreme, re-check the bore diameter entry and units, because a mm vs cm mistake can change results drastically.

What efficiency should I use if I have no data?

Use 85% for a practical baseline. If you want to be conservative, use 75% to account for higher friction, restrictions, and real-world variability. If you have measured data or a specific application with known low losses, you can move closer to 90–95%, but do not assume 100% unless you are doing idealized math only.

Why might my real system need higher pressure than the calculator shows?

Common reasons include pressure drops across hoses and valves, higher friction than assumed, misestimated force requirements, and transient spikes during starts, stops, or impacts. If you are near component limits, increase the safety factor and validate with real measurements under load.