How to Measure Millivolts with a Multimeter

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How to measure millivolts with a multimeter comes down to a few steps: turn the dial to the millivolt range, connect the black lead to COM and the red lead to the voltage jack, then read the display. A millivolt is one thousandth of a volt, so the reading is a small number that is easy to misread if the range or the unit is wrong. This guide walks through the steps, explains how to choose the range, and lists what the sources we opened do not say.

Quick answer

• Set the dial to a DC millivolt setting, and pick the one that sits close to, but not below, the value you expect.
• Put the black lead in COM and the red lead in the jack marked V or positive for voltage.
• Connect the leads to the circuit point and read the display in millivolts.
• If the meter shows a low or overload reading, step up to the next range rather than forcing the meter to read a larger value.

What a millivolt range is

A multimeter’s voltage function usually has several ranges, and some of them are labeled in millivolts. The Fluke guide on measuring DC voltage states that some digital multimeters include DC millivolts, and it describes the millivolt setting as one of the dial positions to use for a voltage measurement. The Hunker guide describes the same setting as a milivolt range on the dial.

The reason to use a millivolt range is resolution. When the signal is small, a range measured in volts shows too few digits to be useful. A range in millivolts gives more digits for the same signal. The two sources do not state a resolution figure for any particular meter, so check the resolution in your meter’s manual before you rely on the last digit.

Millivolt readings are common in low-level signals, such as the output of a sensor or a thermocouple, but the two sources we opened do not describe those applications in detail. We do not give specific sensor values in this guide.

Step-by-step: taking a millivolt reading

1. Check the meter’s function. Confirm whether you need DC or AC. The Fluke guide describes DC voltage measurement, and the Hunker guide describes the millivolt setting in the same context. Use the DC setting for a DC signal.
2. Insert the leads. The Fluke guide says the black lead goes into COM and the red lead into the V and ohm jack. The Hunker guide says to plug the red probe into the hole marked V or plus and the black probe into the hole marked COM or minus.
3. Set the dial. Turn the dial to the millivolt range. The Hunker guide says the setting should be close to, but not over, the maximum voltage you are measuring. The Fluke guide gives a parallel instruction: if the voltage falls within a lower DC millivolt setting, change the dial to that setting.
4. Connect to the circuit. Place the red probe on the positive test point and the black probe on the negative test point. The Fluke guide describes this pairing for DC checks.
5. Read and confirm. Read the display, confirm the unit on the screen says mV, and compare the value with what you expect from the circuit.

Confirm the unit before you write down the value. A reading of 250 on a millivolt range is 0.25 V, and a reading of 250 on a volt range is 250 V. The two readings look alike on a small display, so check the unit label each time.

Choosing the right range

If you do not know the expected value, start at a higher range and step down. The Hunker guide suggests that the setting sits close to the voltage you measure, which implies a range just above it. The Fluke guide suggests moving to a lower millivolt setting only when the voltage falls within that lower range.

Both sources imply that the meter should not be pushed past its range. If the display shows an overload indication, the range is too low for the signal, and the next step is to select a higher range. Neither source describes what the overload symbol looks like on every meter, so refer to your manual for the symbol your meter uses.

Do not change the function dial while the leads are connected to a live circuit. The sources do not describe a specific risk for millivolt ranges, but the general rule applies to every function and range change.

Common mistakes

• Leaving the red lead in the current jack. The Fluke guide warns against placing the red probe in the A input when you mean to measure voltage. A current jack is not the right place for a voltage reading.
• Using a volt range for a small signal. A millivolt value on a range built for volts can show too few digits. Select the millivolt range that fits the signal.
• Reading the wrong unit. Read the unit on the display. A mV label and a V label change the value by a factor of one thousand.
• Assuming every meter has the same ranges. The Hunker guide notes that meters differ in their ranges, so check the range list in your manual.

Checking your result

A millivolt reading is only as good as the connection. Keep both probes firmly on the test points and avoid touching the metal tips with your fingers, because the contact resistance can change a small reading. If the value jumps when you move a lead, repeat the measurement at the same point before you draw any conclusion.

When a reading is unexpected, compare it with a second method. The sources we opened do not describe a cross-check procedure, so this recommendation is general advice rather than a sourced method. For a broader view of how voltage testers and meters are used, see how do voltage testers work and how to use a non contact voltage detector.

How we chose

We wanted sources that describe the millivolt setting in plain terms and that are not product sales pages. We opened two readable pages. The first is a Fluke guide on measuring DC voltage with a digital multimeter, which includes the lead connections, the millivolt setting, and the advice to choose a lower millivolt setting when the voltage falls within it. The second is a Hunker guide on measuring millivolts, which covers the dial setting, the lead connections, and the advice to set the range close to, but not over, the measured voltage.

The two pages overlap on the basic steps and differ in detail. We used the points they share and noted the gaps. We did not use any search snippet as a source for these steps.

What we could not verify

• The sources do not give the resolution of a millivolt range on any specific meter. We did not state a resolution figure.
• The sources do not describe the overload symbol on all meters. Check your manual.
• The Hunker guide describes the lead connections in general terms and does not name a dedicated millivolt jack. We did not state that a separate mV jack exists on any model.
• The sources do not describe a sensor or thermocouple procedure, so we do not give one here.
• The sources do not state the input impedance of the millivolt ranges, so we do not compare loading effects.

Frequently asked questions

Do I need a special meter to measure millivolts?

The Fluke guide states that some digital multimeters include DC millivolts. A meter without a millivolt range can only read volts, so check whether your model has the setting.

What does it mean if the display shows a 1 or OL?

Neither source explains the symbol in full. In general, it means the value is over the range you selected, so move to a higher range. Confirm with your manual.

Can I measure AC millivolts?

The sources we opened describe DC millivolt measurement. We do not state an AC millivolt procedure, so check your meter’s manual for an AC millivolt range before you attempt it.

Why does the reading change when I move the leads?

The sources do not explain this effect. A loose connection is a common cause of unstable readings, so reseat both leads and repeat the measurement.

Is a millivolt reading the same as a volt reading?

No. A millivolt is one thousandth of a volt. Convert the value before you compare it with a volt figure, and keep the unit with the number.

Bottom line

Choose a DC millivolt range close to the expected value, keep the black lead on COM, and step up a range whenever the display shows an overload. Confirm the unit before you record the reading.

Sources

• Fluke, How to Measure DC Voltage with a Digital Multimeter: https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-dc-voltage-with-a-digital-multimeter (opened 2026-10-30)
• Hunker, How to Measure Millivolts: https://www.hunker.com/12526536/how-to-measure-millivolts/ (opened 2026-10-30)