# What is a Digital Multimeter?

A digital multimeter, or DMM, measures and verifies multiple electrical stimuli, including voltage, current and resistance. It’s a daily diagnostic tool used by technicians and electrical engineers and combines the features of a voltmeter, ammeter and ohmmeter. A digital multimeter typically includes probes, clamps or leads, which are inserted into inputs on the instrument and then connected to the device under test to make a measurement.

## Why are digital multimeters used?

A DMM is primarily used to verify one of the three factors of Ohm’s Law voltage (volts), current (amps) and resistance (ohms). This simple equation, expressed below, is commonly used by electrical engineers during diagnostic testing.

V = I x R

V = voltage

I = current

R = resistance

Engineers in the lab and in the field also use digital multimeters to verify the state of a system or circuit for safety purposes. For instance, voltages in excess of 42V or currents in excess of 10 mA can provide painful shocks, and in some cases, be lethal. Resistances are also rated for certain powers (watts) and can get hot when driving higher currents and voltages. Digital multimeters essentially help engineers verify that a device under test is safe to work on.

## Types of digital multimeters

General purpose digital multimeter

General Purpose Multimeter Used By Used To Form Factor Overview
Beginners and Hobbyists Troubleshooting simple circuits and get a general idea of what is and isn't working. Handheld They don't provide a high degree of accuracy but readings are fool proof.

Often used by hobbyists, these DMMs measure voltage, resistance, continuity and current to troubleshoot simple circuits. They don’t provide a high degree of accuracy—just a general idea of what’s working. Simplicity is key and readings are fool proof.

Handheld digital multimeter

Handheld Digital Multimeter Used By Used To Form Factor Overview
Electricians, electrical contractors and HVAC specialists Make measurements and troubleshoot potentially hazardous system in the field. Handheld Handheld DMMs should be used when mobility is required.

Also known as digital voltmeters, handheld digital multimeters are used by electricians, electrical contractors and HVAC specialists to make measurements and troubleshoot potentially hazardous systems in the field. Handheld DMMs should be used when mobility is required.

Advanced Digital Multimeter Used By Used To Form Factor Overview
Electrical and electronic engineers Perform more advanced measurements and gain confidence in their designs. Bench Top These DMMs are extremely precise and have a variety of advanced functionality

Also known as bench DMMs or commercial DMMs, these instruments are used by electrical and electronic engineers to perform more advanced measurements and gain confidence in their designs. These instruments are extremely precise and have a variety of advanced functionality, including the ability to program automation, slow or speed up measurements to observe low-level or transient signal behavior, and interface with other instruments.

Compact digital multimeter

Compact Digital Multimeter Used By Used To Form Factor Overview
Electrical and electronic engineers Perform more advanced measurements and gain confidence in their designs. Rack Mounted Used when precise measurements are needed, but space is limited.

These multi-channel multimeters are used in manufacturing when precise measurements are needed, but equipment space is limited. They embed cards with switches and mux to "squeeze" tens or even hundreds of channels into a single mainframe.

## Digital multimeter vs. oscilloscope

A digital multimeter allows you to read the voltage at any one moment in time, but oscilloscopes show how the voltage changes over time by graphically displaying a waveform. Oscilloscopes are often used over digital multimeters when troubleshooting more complex circuits.

Digital Multimeter Used to: Circuit type:
Read the voltage at any one moment in time. Simple Circuits
Oscilloscope Used to: Circuit type:
Measure how the voltage changes over time. Complex Circuits

## How to Choose a Digital Multimeter

When it comes to choosing the right digital multimeter for your application, there are a number of considerations, starting with where you will be using it. You’ll also want to look at accuracy, speed and the number of channels needed to ensure the instrument will meet the demands of your job.

## How to use a digital multimeter

A digital multimeter is very easy to set up and use to run tests in the lab. Simply follow the six steps below to set up your digital multimeter and start measuring a device under test (DUT).

1. Inspect your digital multimeter and DUT for signs of physical damage.
2. Insert the appropriate probes into the DMM inputs (the probes and inputs are typically color coded for ease of use).
3. Set your DMM to resistance, voltage or current mode, depending on what you’re measuring.
4. Test that your DMM is working correctly with a known voltage source.
5. Hold the tip of the probes or clamps to the positive and negative terminals of the DUT to make your measurements.
6. As you’re working, watch the DMM’s display screen for safety warnings.

Note: The steps above cover the basics of how to use a digital multimeter, but engineers should always consult the model-specific instruction manual before operating a digital multimeter to ensure practices are safe and measurements are accurate.

## Digital multimeter resources

Ready to take your DMM knowledge to the next level? Learn more about digital multimeters and how to use them in the Tektronix Learning Center, where you can find these and many other resources:

If you’re thinking of purchasing an advanced digital multimeter, view our DMM comparison table, browse our collection of digital multimeters or request a product demo.