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How to Measure Voltage in a Series Circuit Using Multimeter

The person typing “how to measure voltage in a series circuit using multimeter” wants to know how to read the voltage across each component in a loop where the components are wired one after another. You do not break the loop for this. You set the meter to voltage, place its leads across one component at a time, and read the value on the display. The voltage across each part is a separate reading, and the readings should add up to the source voltage when the circuit is working as expected.

Quick answer

• Set the dial to voltage (use the AC symbol for AC circuits and the DC symbol for DC circuits).
• Plug the black lead into COM and the red lead into the V jack, not the A jack.
• Touch the leads to the two ends of one component, read the display, then move the leads to the next component.
• Do not move the meter into the current path. Voltage is measured across a part, not through it.

What a series circuit means for voltage readings

In a series circuit, the components are connected end to end, so there is only one path for current. The Keysight engineering guide on series and parallel circuits states that “the same current flows through each component in the circuit without any branching off.” Because the same current passes through every part, each part develops its own voltage drop. Your job with the meter is to measure that drop at each part.

The same guide gives the rule for total resistance in a series string: “Total resistance is the sum of all resistances,” written as R_total = R1 + R2 + … + Rn. That rule matters here because a larger resistor in the string will normally show a larger share of the voltage. The guide is the source for the circuit rule. The actual voltage on each part still has to be measured on your circuit, not calculated from the rule alone.

Equipment and settings

Any digital multimeter with a voltage function can do this job. Fluke’s guide to a multimeter describes the common terminals on most meters: the common (COM) terminal, the voltage (V) terminal, and the current (A) terminal. For voltage you use COM and V. The Fluke article on measuring AC voltage warns that a test lead placed in an A or mA input will short the measurement circuit, so check the lead position before you power the circuit.

Set the dial to the voltage function that matches the circuit. Fluke’s AC voltage guide says to turn the dial to the ṽ symbol for AC and its DC voltage guide uses the ⎓ symbol for DC. If you do not know the voltage, start on the highest voltage range. Many modern meters use autorange, which selects the range for you. Fluke’s DC guide says that “Modern DMMs default to Autorange based on the function selected on the dial.” If your meter does not autorange, press the RANGE button until the range you want is selected.

Step-by-step: measure the voltage across each component

1. Confirm the circuit is powered and safe to work on. Voltage readings are taken on a live circuit, so keep your fingers behind the probe guards and keep the lead tips from touching each other.
2. Set the dial. Choose AC or DC voltage and a range that covers the source voltage.
3. Insert the leads. Put the black lead in COM and the red lead in the V jack.
4. Measure the source first. Place the leads across the power source. This gives you the total voltage for the string. Write the reading down.
5. Measure the first component. Touch one probe to each end of the first component. Read the display and record the value.
6. Measure the next component. Move the leads to the two ends of the second component and record the value. Repeat for every component in the string.
7. Check the total. Add the component readings. They should be close to the source reading. A large gap points to a bad connection, a bad probe contact, or a component that is not what you expected.
8. Remove the leads in the correct order. Fluke’s AC voltage guide says to remove the red lead first and the black lead second when you finish.

Fluke’s AC voltage guide also advises that “AC voltage does not have polarity,” so for AC the lead order does not change the reading. For DC, Fluke’s guide says that if the probes touch opposite terminals, “a negative symbol will appear in the display.” That is a polarity signal, not an error, and it tells you which side of the component is more positive.

Reading the numbers

A series string divides the source voltage among its parts. If you measure a 12 V source and three parts, the three readings should total about 12 V, with small differences caused by meter accuracy and contact resistance. If one reading is near the full source voltage and the others are near zero, the part with the full reading is likely open, so the current path is broken there. If every reading is zero, check the source, the fuse or breaker, and whether the leads are on the right jacks.

When the readings look wrong, do not assume the meter is at fault. Check the probe connection first. Then confirm that the dial is on voltage, not resistance or current. Fluke’s multimeter guide notes that you should always check the meter’s fuse before making a current measurement, which is a useful habit before any work with the meter.

Common mistakes

• Putting the leads in the current jacks. A meter with leads in the A jack is set up for current, not voltage. Fluke’s guide warns about this for voltage work.
• Breaking the loop to measure voltage. That is a current measurement method. For voltage, keep the circuit closed and place the leads across the part.
• Using a low range on an unknown voltage. Start high and step down.
• Reading one part and assuming the rest. Each part can have a different drop, so measure each one.

How we chose

This guide follows the measurement steps from manufacturer and engineering sources that we opened and read. We chose the steps that apply to every digital multimeter with a voltage function, then used the series rule from the Keysight guide to explain why each part shows its own reading. We did not use retail pages or product listings as sources for any technical statement.

What we could not verify

• The Klein Tools MM300 instruction manual is a PDF that the fetch tool could not read as text, so no MM300-specific steps are quoted here. Check your own meter’s manual for its exact jack labels and range limits.
• The Fluke pages we opened do not describe measuring voltage in a series string by name. The series procedure above is built from the general voltage steps and the series rule.
• No device-specific voltage values for any particular meter or circuit are given here, because the sources we opened do not list them.

FAQ

Do I need to turn the circuit off to measure voltage in a series circuit?

No. Voltage is measured across a component with the circuit powered. Turning the circuit off is the rule for resistance measurements, as Fluke’s guide to using a multimeter says to turn off circuit power before testing resistance.

Why do the voltages across the parts not match the source?

Small differences come from meter accuracy and loose contacts. A large gap usually means a bad connection or a part that is not behaving as expected. Recheck each probe contact before you change any part.

Which jack do I use for voltage?

Use COM for the black lead and the V jack for the red lead. Do not use the A jack for voltage.

Can I measure the series voltage with the meter in a current setting?

No. The current setting puts the meter in the current path and can blow the fuse or short the circuit. Voltage needs the voltage setting.

What if the meter reads zero on every part?

Check the source reading first. If the source is good, check the fuse or breaker, the probe jacks, and whether the leads are making contact.

Is AC or DC voltage different for a series string?

The steps are the same. For DC, the polarity of each reading matters, and the display shows a negative sign when the probes are reversed. For AC, polarity does not apply.

Bottom line

To measure voltage in a series circuit, keep the loop closed, set the meter to voltage, and place the leads across each component one at a time. Compare the parts against the source reading. The voltage tells you where the drop is happening.

Related guides

For a wider view of meters you can use for this kind of work, read our guide to Extech multimeters and our guide to Fluke clamp meters for automotive work.

Sources

• Fluke, “How to Measure AC Voltage with a Digital Multimeter”: https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-ac-voltage-with-a-digital-multimeter (opened 2026-10-28)
• 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 2026-10-28)
• Fluke, “How to Use a Multimeter: A Comprehensive Guide”: https://www.fluke.com/en-us/learn/blog/maintenance-monitoring/how-to-use-a-multimeter-guide (opened 2026-10-28)
• Fluke, “What Is Ohm’s Law?”: https://www.fluke.com/en-us/learn/blog/electrical/what-is-ohms-law (opened 2026-10-28)
• Keysight, “Series and Parallel Circuits: Engineering 101 Guide”: https://www.keysight.com/used/kr/en/knowledge/guides/series-and-parallel-circuits (opened 2026-10-28)