Hydrostatic Pressure & Tank Level Calculator

How to use this calculator

Enter the liquid height and density to get the hydrostatic pressure at the bottom. To set up a level transmitter, enter the maximum level to get its upper range value. To read level from a pressure gauge, press × on the level and type the pressure.

The formula

P = ρ × g × h

• ρ — liquid density (kg/m³)
• g — standard gravity, 9.80665 m/s²
• h — height of liquid above the measuring point (m)

Worked examples

Water tank, 5 m level

P = 1000 × 9.80665 × 5 = 49,033 Pa = 0.490 bar (7.11 psi)

Diesel tank (ρ ≈ 832 kg/m³), 3 m level

P = 832 × 9.80665 × 3 = 24,477 Pa = 0.245 bar

The same pressure would show only 2.5 m on a transmitter calibrated for water — always range for the real density.

Typical densities at about 20 °C

Liquid	Density (kg/m³)
Water	998
Sea water	1,025
Diesel	820 – 845
Petrol	720 – 775
Ethylene glycol	1,113
Sulphuric acid (98%)	1,830

Ranging a level transmitter

1. Calculate the pressure at minimum level (often 0) and maximum level.
2. If the transmitter is mounted below the tank nozzle, add the liquid head between the nozzle and the transmitter (zero elevation).
3. Enter these as the 4 mA and 20 mA values — then use the 4–20 mA scaling calculator to check readings.

A useful rule: 1 m of water ≈ 0.098 bar ≈ 1.42 psi ≈ 9.81 kPa.

Frequently asked questions

How do I calculate pressure at the bottom of a tank?

Multiply density × gravity × height. Water at 5 m depth gives 1000 × 9.80665 × 5 = 49,033 Pa, or about 0.49 bar.

How do I convert pressure to tank level?

Level = pressure ÷ (density × g). Press × on Liquid level and type the pressure reading. Always use the actual liquid density.

Does the tank shape matter?

No. Hydrostatic pressure depends only on liquid height and density, not on the tank's shape or volume.

Is this gauge or absolute pressure?

Gauge pressure, as read by a vented level transmitter. Add atmospheric pressure (about 1.013 bar) for absolute.

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