How A Multimeter Measures Voltage

By Ivan Piltz | Updated 27 October 2022

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A multimeter is a versatile tool that can measure voltage, current, and resistance. It's an essential piece of equipment for any tradesman or electrician. But how does a multimeter measure voltage?

How does a multimeter measure voltage?

The way a multimeter measures voltage is by using a process called "voltage division." This is where the multimeter takes the voltage of the circuit and divides it by the resistance of the circuit. The resulting number is the voltage that the multimeter displays on its screen.

What is voltage?

To understand how a multimeter measures voltage, it's important to understand what voltage is. Voltage is the difference in electrical potential between two points. It's typically measured in volts (V). The standard unit for measuring voltage is the volt.


A multimeter uses its probes to measure voltage.

How to measure voltage with a multimeter?

To measure voltage with a multimeter, you first need to set the dial to the "V" setting. Then, you need to connect the probes to the circuit. The red probe goes to the positive terminal, and the black probe goes to the negative terminal.

Once the probes are connected, you can read the voltage on the screen.To measure DC voltage, the black lead of the multimeter must be connected to the point being measured while the red lead is connected to the positive terminal of the power supply. The power supply can be either a battery or an external power source.

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What is a multimeter?

A multimeter is an electrical testing device that is used to measure voltage, current, and resistance. The three main types of multimeters are analog, digital, and clamp. Analog multimeters use a needle and dial to display readings while digital multimeters use an LCD display. Clamp multimeters measure current by clipping around a conductor without interrupting the circuit.

Multimeters can measure both AC and DC voltage. AC voltage is measured in root mean square (RMS) while DC voltage is measured in peak-to-peak (P-P). Most multimeters will have two settings for measuring AC voltage, one for measuring RMS voltage and one for measuring P-P voltage.

To measure AC voltage, the multimeter must be set to the correct setting and the black lead of the multimeter must be connected to the common ground while the red lead is connected to the point being measured.

Multimeter and circuit board

A multimeter checking current in laptop circuit board.

How accurate is a multimeter?

Multimeters are generally quite accurate, but there are a few factors that can affect their accuracy.

One is calibration; if your multimeter isn't properly calibrated, it might not give you an accurate reading.

Another factor is interference; if there's electrical noise present, it can throw off your multimeter's readings.

Finally, temperature can also affect accuracy; if it's too cold or too hot, your multimeter might not function properly. 


Now that you know how a multimeter works, you can better understand how to use this essential tool. Be sure to always consult your owner's manual before using a multimeter and never attempt to measure voltages above 30 volts without proper safety precautions.