4-20mA to Pressure Calculator

The 4-20mA to Pressure calculator helps you find pressure from a transmitter's current signal. It works with any linear 4-20 mA pressure transmitter range.

A 4 mA signal equals the low pressure value. A 20 mA signal equals the high pressure value. The calculator finds the pressure between these two points.

You can use it for 4-20mA to psi conversion, pressure transducers, process sensors, and industrial control systems. It can also work in reverse for pressure to milliamps conversion.

4-20mA to Pressure Formula

The standard formula used by our calculator is:

P = Pmin + ((I - 4) / 16) × (Pmax - Pmin)

Here, P is the calculated pressure. I is the measured current in mA. Pmin is the pressure at 4 mA. Pmax is the pressure at 20 mA.

The current span is 16 mA because:

20 - 4 = 16 mA

For example, a 0-100 psi transmitter has 0 psi at 4 mA and 100 psi at 20 mA.

How to Use Online 4-20mA to Pressure Calculator

1. Enter the pressure value at 4 mA in the Pmin field.
2. Enter the pressure value at 20 mA in the Pmax field.
3. Select the pressure unit, such as psi, bar, kPa, MPa, kgf/cm², or in H₂O.
4. Enter the measured loop current in mA.
5. Click the calculate button to get the pressure output.

The calculator also checks whether the current is within the normal 4-20 mA range. Values below 4 mA or above 20 mA are marked as out of range.

Example 4-20mA to Pressure Calculation

Suppose a pressure transmitter has a range of 0 to 100 psi. The measured output is 12 mA.

First, find the pressure span:

Pmax - Pmin = 100 - 0 = 100 psi

Next, find the current fraction:

(I - 4) / 16 = (12 - 4) / 16 = 8 / 16 = 0.5

Now calculate pressure:

P = 0 + (0.5 × 100)

P = 50 psi

So, a 12 mA signal equals 50 psi for a 0-100 psi transmitter.

Final Verdict

The 4-20mA to Pressure calculator uses simple linear scaling. It converts a measured 4-20 mA signal into pressure based on the transmitter's low and high range.

The key formula is:

P = Pmin + ((I - 4) / 16) × (Pmax - Pmin)

This method is useful for 4-20mA to psi conversion, pressure sensors, industrial transmitters, and process measurement systems.

The same 4-20 mA signal can also be scaled to voltage. For example, control systems may use circuits for converting 4-20mA to 2-10V, 4-20mA to 1-5V, or other signal ranges. Those are separate signal-scaling conversions and aren't part of the pressure calculation itself.

FAQs

What is a 4-20mA to Pressure calculator?

It converts a linear 4-20 mA transmitter signal into a pressure value using the transmitter's minimum and maximum pressure range.

What pressure does 4 mA represent?

4 mA represents the transmitter's lower range value, or Pmin. For a 0-100 psi transmitter, 4 mA represents 0 psi.

What pressure does 20 mA represent?

20 mA represents the transmitter's upper range value, or Pmax. For a 0-100 psi transmitter, 20 mA represents 100 psi.

How do you convert 4-20mA to psi?

Use:

P = Pmin + ((I - 4) / 16) × (Pmax - Pmin)

For a 0-100 psi range at 12 mA, the result is 50 psi.

Can I convert pressure back to milliamps?

Yes. Use:

I = 4 + ((P - Pmin) / (Pmax - Pmin)) × 16

This gives the expected transmitter current for a known pressure.

Is 4-20mA always linear?

This calculator assumes a linear 4-20 mA pressure transmitter. Nonlinear transmitters or special sensor scaling may require a different calculation.

Can this calculator convert 4-20mA to voltage?

No. This calculator is designed for current-to-pressure and pressure-to-current conversion. 4-20mA to 0-10V, 4-20mA to 0-5V, and 0-10V to 4-20mA require separate electrical signal-scaling formulas or converter circuits.