Current Shunt Measurement

I = Vshunt / Rshunt

Quick answer

This calculator solves I = V_shunt / R_shunt for Measured Current. With Shunt Voltage 0.6 V, Shunt Resistance 50 mΩ, the result is 12 A. It solves in 3 directions, so you can enter the values you have and get the one you need.

Calculator

Measured Current (A)
—

Formula

I = V_shunt / R_shunt

Description

A current shunt resistor converts current to a measurable voltage drop using Ohm's Law. The shunt resistance is chosen to be very small (milliohms) to minimize power dissipation and voltage burden on the circuit, while producing a voltage large enough for accurate measurement. Current sense amplifiers (INA219, INA226, MAX9611) amplify the millivolt shunt voltage for ADC measurement. High-side sensing (shunt between supply and load) is preferred for detecting ground faults but requires a differential amplifier that rejects the common-mode supply voltage.

Variables

  • I — Current through the shunt (A)
  • V_shunt — Voltage drop across the shunt (V)
  • R_shunt — Shunt resistance (Ω)

Practical Notes

Common shunt values: 1-100 mΩ. A 10 mΩ shunt carrying 5 A produces 50 mV and dissipates 250 mW. For 1% current accuracy, the shunt must have better than 1% resistance tolerance and low temperature coefficient (< 50 ppm/°C). Four-terminal (Kelvin) connection to the shunt eliminates lead resistance error. PCB trace resistance can serve as a shunt for low-cost current sensing, but has ±20% tolerance and +0.39%/°C temperature coefficient.

Symbols and units

Symbol Meaning Default unit Accepted units
I Measured Current A pA, nA, µA, mA, A, kA
V Shunt Voltage mV pV, nV, µV, mV, V, kV
R Shunt Resistance mΩ mΩ, Ω, kΩ, MΩ

Step by step

  1. 1. What you know: Shunt Voltage 0.6 V, Shunt Resistance 50 mΩ
  2. 2. The relation: I = V_shunt / R_shunt
  3. 3. Substitute: V = 0.6 V, R = 50 mΩ
  4. 4. Result: Measured Current = 12 A

Related quantities from the same inputs

  • P = V × I = 7.2 W

Worked examples

Minimum range

Given: Shunt Voltage 10 mV, Shunt Resistance 0.1 mΩ

Result: Measured Current = 100 A

Low range

Given: Shunt Voltage 100 mV, Shunt Resistance 1 mΩ

Result: Measured Current = 100 A

Typical

Given: Shunt Voltage 0.6 V, Shunt Resistance 50 mΩ

Result: Measured Current = 12 A

High range

Given: Shunt Voltage 0.9 V, Shunt Resistance 0.5 Ω

Result: Measured Current = 1.8 A

Maximum range

Given: Shunt Voltage 9 V, Shunt Resistance 5 Ω

Result: Measured Current = 1.8 A

Solving for each variable

Solve for Measured Current

Shunt Voltage 10 mV, Shunt Resistance 0.1 mΩ → 100 A

Solve for Shunt Voltage

Measured Current 2 mA, Shunt Resistance 0.1 mΩ → 0.2 µV

Solve for Shunt Resistance

Measured Current 2 mA, Shunt Voltage 10 mV → 5 Ω

How Measured Current changes with Shunt Voltage

Shunt Voltage (input) Measured Current (result)
60 mV 1.2 A
150 mV 3 A
0.3 V 6 A
0.45 V 9 A
0.6 V 12 A
0.9 V 18 A
1.2 V 24 A
2.4 V 48 A
4.2 V 84 A
6 V 120 A

The same result in other units

Unit Value
mA 12000
A 12
kA 0.012

Embed this calculator

Paste this into any page. It keeps working when this page updates, and credits the source.

<iframe src="https://vbatpower.com/embed/current-shunt/" width="100%" height="460" style="border:1px solid #1f2a37;border-radius:12px" loading="lazy" title="Current Shunt Measurement"></iframe>
<p><a href="https://vbatpower.com/formulas/current-shunt/">Current Shunt Measurement</a> Calculator by vbatpower.com</p>

Frequently asked questions

How do you calculate Current Shunt Measurement?

Use I = V_shunt / R_shunt. With Shunt Voltage 0.6 V, Shunt Resistance 50 mΩ, Measured Current works out to 12 A.

What is the formula for Current Shunt Measurement?

The formula is I = V_shunt / R_shunt. A current shunt resistor converts current to a measurable voltage drop using Ohm's Law.

How do you find Shunt Voltage when you know the other values?

Rearrange for Shunt Voltage: with Measured Current 2 mA, Shunt Resistance 0.1 mΩ, Shunt Voltage is 0.2 µV.

How do you find Shunt Resistance when you know the other values?

Rearrange for Shunt Resistance: with Measured Current 2 mA, Shunt Voltage 10 mV, Shunt Resistance is 5 Ω.

What units does Current Shunt Measurement use?

Measured Current is shown in mA, A, kA. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

Related Concepts

All Sensors & ADC formulas →
ADC Resolution (LSB) ADC Theoretical SNR Steinhart-Hart Temperature Wheatstone Bridge Linear Sensor Transfer Function Oversampling SNR Improvement RTD Callendar-Van Dusen Current Shunt Measurement

Need more features?

Save calculations, import telemetry data, simulate battery discharge, and collaborate with your team.

Try the App