4-20 mA transmitter current output can be converted to the voltage within a specified range, from 0 to a maximal amplitude **V**_{max}, as shown in the following picture:

# 4-20mA Formulas and Examples

**I**the output current and

**V**the Voltage—or other physical variables (PV) —between

**V**

_{min}(which is usually 0) and

**V**

_{max}; the conversion formulas are as follows:

**I [mA] = ( ( (V − V**_{min}) / ( V_{max}− V_{min}) ) × 16 ) + 4**V [Voltage] = ( (I − 4 ) / 16) × ( V**_{max}− V_{min}) + V_{min}**PV [units] = ( (I − 4 ) / 16) × ( PV**_{max}− PV_{min}) + PV_{min}

Where,

I is the current,

V is the voltage,

PV is the Process Variable

min is the Lower Range Value of the respective signal

max is the Upper Range Value of the respective signal

Note that the values and units of **min** and **max** are units must be same.

**Example 1 :**

#### A Analog output card gives an output voltage of 2.5V and its overall range is 0-5V. calculate the equivalent 4-20mA current value.

I = ( ( (**V** − **V**_{min}) / ( **V**_{max} − **V**_{min}) ) × 16 ) + 4

I = ( ( (**2****.5** − **0**) / ( **5** − **0**) ) × 16 ) + 4

I = 12 mA

**Example 2 :**

#### A transmitter output range is 13.5mA and its output range is 4-20mA. Calculate equivalent voltage. consider 0-10V is the output voltage range.

V = ( (**I** − 4 ) / 16) × ( **V**_{max} − **V**_{min} ) + **V**_{min}

V = ((13.5 – 4)/16 x (10 – 0 ) + 0

V = 5.9375 V

**Example 3 :**

#### A Flow transmitters output current is 16.5mA and its range is 0-1500 m3/hr. Calculate the equivalent flow rate value.

PV = ( (**I** − 4 ) / 16) × ( **PV**_{max} − **PV**_{min} ) + **PV**_{min}

PV = ( (**16.5** − 4 ) / 16) × ( **1500** − **0 **) + 0

PV = 1171.87 m3/hr

**Also Read : 4-20mA Transmitter Principle**

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## 12 comments

Thanx, Realy it is important for me.

Thanks very much sir, this is very important.

pls how do i print it.

formula wrong ex: range -50 to 50 psi i get 12 mA what is the pv value?

Hi Balajee, Formula Working fine. Please see : PV = [ (12-4)/16 X { 50- (-50) } ] + (-50) = ( 0.5 X 100 ) – 50 = 0. Also Click Here to Use online Calculator for fast calculations.

yes Mr S Bharadwaj reddy its by mistake. Thanks 4 reply

I(mA)=16/(Vmax-Vmin)(V-Vmin)+4Vmax/(Vmax-Vmin)

0 psi

How amazing very good effort.

thanks

thank you brother

how to calculate the % of valve opening at milli ampere 4 to 20

Hi, For 4-20mA to 0 – 100 % Conversion : CLICK HERE