Basic Functions and Use of A Digital Multimeter

Last updated on October 22nd, 2026.

A digital multimeter measures electrical quantities and helps diagnose circuit problems. Learning its basic functions is part of training as an electrician apprentice.

The controls and multimeter symbols differ across brands, so learn the purpose of each setting on your meter.

What Is A Digital Multimeter?

A digital multimeter, or DMM, is test equipment used to diagnose electrical or electronic problems. It takes analog information and uses an analog to digital converter to convert it into a digital signal which reads out on the display.

You can use a digital multimeter for measuring the following:

• AC voltage
• DC voltage
• Current (both AC current and DC current)
• Resistance
• Temperature
• Frequency
• Capacitance

The available measurements depend on the type of digital multimeter you have. At a minimum, you should be able to measure voltage, resistance and current with any digital multimeter.

How To Use A Digital Multimeter To Test Voltage

Testing a circuit (or source of power) for voltage is the most common use of a digital multimeter. The steps differ for AC and DC circuits.

DC or Direct Current Circuits

1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
2. Turn on your multimeter and set the selector switch to the V with the solid and dashed line (VDC).
3. Connect the test leads to the circuit: black to the negative potential point (which is the circuit ground) and red to a positive potential point.

   

The display should show the voltage of the source (battery) or circuit. A – symbol before the reading means the polarity is backward, so switch the leads. If no reading appears, check the selected setting and lead connections. A continued lack of a reading means the source is dead or the circuit is off. If it still does not read, the multimeter is broken (choose one of the best multimeters on the market, as some meters are poor quality).

AC or Alternating Current Circuits

1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
2. Turn on your multimeter and set the selector switch to the ∨ with the wave.
3. For AC, lead placement does not affect the measurement. You need to know the expected readings for the conductors and receptacles you are testing.

I found a YouTube video that explains the basics of using a digital multimeter. If you prefer written instructions, the resources below cover its functions and applications.

For more information, Fluke has a digital multimeter fundamentals library explaining DMM functions and how to use them for specific applications. Check it out here.