Pressure Loss Calculator

About the Pressure Loss Calculator

Converts a head loss in metres into a pressure in kPa and psi, and adds static lift to give total dynamic head for pump selection.

How to use this calculator

1. Enter the fluid density \(\rho\) in \(\text{kg/m}^3\).
2. Enter gravity \(g\) in \(\text{m/s}^2\), usually \(9.81\).
3. Enter the head loss \(h\) in meters, then calculate pressure with \(P = \rho g h\).
4. If needed, compare the result with total dynamic head, which is the total height a pump must overcome including losses.

The formula explained

The formula \(P = \rho g h\) computes the pressure corresponding to a given head loss. It shows that pressure increases when the fluid is denser, gravity is stronger, or the head loss is larger.

• P = pressure loss or pressure difference, in \(\text{Pa}\)
• \(\rho\) = fluid density, in \(\text{kg/m}^3\)
• g = acceleration due to gravity, in \(\text{m/s}^2\)
• h = head loss, in \(\text{m}\)

Step by step method

1. Write down the density \(\rho\), gravity \(g\), and head loss \(h\).
2. Multiply \(\rho\) by \(g\), then multiply that result by \(h\).
3. Check the units, because \(\text{kg/m}^3\) times \(\text{m/s}^2\) times \(\text{m}\) gives \(\text{Pa}\).

Worked example

Problem. A water pipe has a head loss of \(3.2\) m. If the water density is \(1000\) \(\text{kg/m}^3\) and gravity is \(9.81\) \(\text{m/s}^2\), what pressure loss does that correspond to?

1. Use \(P = \rho g h\).
2. Substitute the values: \(P = 1000 \times 9.81 \times 3.2\).
3. Compute \(P = 31{,}392\) \(\text{Pa}\), which is about \(31.4\) \(\text{kPa}\).

Tips and common mistakes

• Be careful with units, especially if head is given in feet instead of meters.
• This formula gives pressure from head loss, so a larger head loss means a larger pressure drop.

Frequently asked questions