How to Use a Multimeter to Check Voltage (Digital & Analog)

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Master electrician Jesse Kuhlman explains when to measure AC or DC currents with your multimeter

Co-authored by Jesse Kuhlman and Amy Bobinger, BA

Last Updated: December 5, 2025 Fact Checked

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• Digital Multimeter
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• Analog Multimeter
|
• Parts of a Multimeter
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• AC vs. DC
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• Safety Tips
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• Choosing a Multimeter
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• Video
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• Expert Q&A
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• Tips
|
• Warnings

|Show more |Show less

If you’ve never tested voltage with a multimeter before, you might be staring at all of the different numbers, symbols, and buttons on the device and wondering what exactly you’re supposed to be doing with them. Don’t worry! We talked to electrician Ricardo Mitchell and master electrician Jesse Kuhlman to help you figure out exactly how to use a digital or analog multimeter (along with must-know safety tips).

How do you test voltage with a multimeter?

Master electrician Jesse Kuhlman says to use AC if you’re measuring around the house, or DC if you’re measuring low-powered objects. Here’s how to do it:

1. Turn off the power and select AC or DC with the multimeter selector knob.
2. Select the expected range if you have a manual dial.
3. Plug the black lead into the COM port.
4. Put the red lead into the mAVΩ port (small voltage) or the 10A port (high voltage).
5. Touch the black lead to the negative or neutral side of whatever you’re testing.
6. Touch the red lead to the positive side.
7. Check the reading before removing the red lead first, then the black lead.

Steps

Section 1 of 6:

Testing Voltage with a Digital Multimeter

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1. 
   1
   Inspect the multimeter and cut the power to whatever you’re testing. Always go over a multimeter carefully before you use it. Look at the leads and make sure the rubber casing isn’t cracked or gouged. Also, inspect the probes to ensure they’re intact and connected securely to the leads. If everything looks okay, use the power button to turn on the multimeter.

   • If you see any damage to the multimeter, don’t try to repair it—that could leave you vulnerable to a dangerous shock. Multimeters are fairly inexpensive, so just replace it with a new one.
   • To avoid electrical shock, ensure your testing area is completely dry before you begin.
   • If you’re testing a battery, remove it from the device and any power sources. If you’re testing a plug, turn off the power first. (For instance, you might flip off the breaker to that area.)
   • Wear rubber-soled shoes and rubber gloves, especially if you’re working with AC power.

   Meet the wikiHow Experts

   Jesse Kuhlman is a Master Electrician, the owner of Kuhlman Electric, and the author of 4 eBooks on home wiring. He specializes in home and residential wiring and generator installation.

   Ricardo Mitchell is the CEO of CN Coterie, a licensed and insured Lead EPA Certified construction company in Manhattan. He has over 10 years of electrical and construction experience.
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   Test (or “ohm out”) the probes. Turn the multimeter to ohms (usually marked with a Ω symbol). Plug the black plug into the COM port on the multimeter and the red plug into the port marked Ω. Hold the probes by the rubber casing (do not touch the metal) and gently tap the probes together.

   • If the reading says 0.5Ω or less, the multimeter is working properly.
   • If the reading is higher, the multimeter is malfunctioning and needs to be replaced.
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3. 
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   Select AC or DC based on the current you’re measuring. The symbol for direct current (DC) is a V with 3 dots or a dash above it. It may also be labeled with something like “DCV.” An alternating current (AC) setting is often labeled with a V and a squiggly line or initials like “ACV.” Turn the dial to the type of current you plan on measuring.

   • If you’re not sure which symbols stand for AC and DC, check the owner’s manual for your multimeter.
   • DC is common in batteries and other low-voltage sources of power. AC is used in buildings, electronics, and anything else that requires multiple currents. Still not sure which to choose? Jump to our section on measuring DC vs. AC voltage.
4. 
   4
   Select the expected voltage range if your meter has a manual dial. On some multimeters, you will see a selection of numbers around the dial. If yours has these numbers, refer to the electronic device or battery you’re testing (or check the user manual) to find the normal voltage it is supposed to have. Then, set the multimeter dial to the next highest setting above the expected voltage.

   • For example, if you have a 12V battery, test it using the 20V setting.
   • If you’re not sure what voltage setting to use, start at the highest one. Work your way back until you see the voltage readout say “1,” “OL,” or “OVER.” This means the range is too low, so click back one setting higher.
   • Many modern multimeters have an autorange feature, meaning they set the proper range once you begin the test.
   • Check the maximum voltage for your multimeter—if you anticipate that whatever you’re testing has a higher voltage than the max, do not attempt to test the current.
5. 
   5
   Plug the black and red probes into the multimeter. The black probe always fits into the COM port on the front of the multimeter, so insert that one first. The remaining ports—usually marked 10A and mAVΩ—are meant for the red plug. Choose the one that fits the kind of current you plan on testing.

   • The mAVΩ port is meant for currents rated at 200 milliamps (mA). If you’re testing a battery or other relatively small power source, use this port.
   • Use the 10A port to test strong currents greater than 200 mA. If you don’t know the strength of the current you are testing, plug the red probe into the 10A port to avoid damaging the multimeter.
6. 
   6
   Connect the test leads to the circuit you’re testing, black probe first. Connect the black probe first, touching the negative or neutral side if there is one. Then, touch the tip of the red probe to the opposite terminal or end of the circuit. The multimeter’s display will change as the current flows through it.

   • To get accustomed to using a multimeter, test it on a battery. Hold the black probe against the negative terminal and the red probe against the positive one.
   • If you’re attempting to test live wires, find the screws pinning the wires in place. Touch the black probe to one screw and the red probe to another.
   • Avoid touching active wires or the metal parts of the probes, since it could lead to an electrical shock. Also, the multimeter could short-circuit if you touch the metal tips of the probes together.
   • If you’re testing a household outlet, check out our section on safety tips before you get started.
7. 
   7
   Adjust the multimeter as needed to get an accurate reading. The multimeter display will change as soon as it detects the active circuit. If you set the dial to the correct setting, you won’t need to do anything else. If you’re not sure what the test subject’s normal voltage is supposed to be, turn the dial down gradually until the number 1 appears, then back the dial up one notch higher.

   • The multimeter range has to be set to the correct maximum voltage for the circuit in order to get the most accurate result possible. If it is set too high, it will have a hard time detecting the voltage of a weaker current.
   • If the multimeter displays a negative number, the probes are reversed. Remove them (red probe first, then black), then put the black probe where the red probe was, and vice versa.
   • If you don’t see any readout, the circuit may not be receiving any electrical power at all. Test the multimeter on something active, such as a battery or outlet, to make sure it still works.
8. 
   8
   Remove the red and black probes when you’re finished. Pull the red probe away from the circuit, then take away the black one. Handle them with caution to avoid coming into contact with the metal tips or bumping the probes together. When you’re ready to stop using the multimeter, unplug the probes by removing the red one first and the black one second.

   • Some multimeters have an auto-shutoff feature. If yours has a power button, turn it off to conserve battery power.
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Section 2 of 6:

Testing with an Analog Multimeter

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1. 
   1
   Change the multimeter to test an AC or DC current. Turn the dial to the proper setting. The AC setting is often indicated by a straight line or a label like ACV. The DC option usually appears as a series of dots or a label like DCV. The setting you need will depend on what you are testing.

   • Use the AC setting to test wall outlets and most electronic devices. DC is for batteries and other low-voltage power sources.
2. 
   2
   Select a high range on the dial for the test. Choose a range according to the regular voltage of the device you wish to test. The voltage is printed on some devices and included in the user manual on others. To get an accurate result while protecting the multimeter from damage, set the dial at the next highest voltage setting available.

   • For instance, most home outlets maintain a 120-volt current. Set the multimeter to 200v or the next closest setting above 120.
   • Most multimeters have fuses that protect them from serious damage, although inexpensive ones sometimes don’t. Using the wrong setting could destroy the multimeter.
   • If you’re unsure what setting to use, start at the highest one and move down until the multimeter reacts.
3. 
   3
   Plug the probes into the ports on the multimeter. Look for a pair of open ports on the bottom left and right corners of the multimeter. The slot marked as -COM is meant for the black probe. Plug the red probe into the slot marked with a plus sign.

   • If you reverse the probes, you won't get an accurate test result. If you notice the multimeter needle moving in the wrong direction, check the probes first.
4. 
   4
   Touch the ends of the probes to the device you are testing. Use the black probe first, holding it to the negative terminal if the device has one. Then, touch the red probe to the positive terminal. Be careful not to touch the metal tips of the probes or any active electrical components that could shock you.

   • You can test the multimeter using a battery first. The positive and negative terminals on the battery are labeled and easy to spot.
   • Handle the probes one at a time to avoid touching the tips and short-circuiting the device.
5. 
   5
   Check the meter and adjust it to get an accurate reading. Analog multimeters have a needle that moves to measure voltage. Watch for the needle to move toward the voltage numbers printed on the multimeter. Analog multimeters also have separate rows of numbers labeled for AC and DC settings, so make sure you’re looking at the correct one. Note the measurement, then consider doing the test a couple more times to ensure you got an accurate reading.

   • If the needle doesn’t move much, turn the multimeter’s voltage setting down a little bit. It often doesn’t react when the voltage setting is too high. Also, make sure the testing device is active.
   • If the needle moves all the way to the right, pull the probes out. Set the multimeter dial to a higher range, then perform the test again. Try to avoid having this happen, since it could damage the multimeter.
6. 
   6
   Unplug the multimeter probes when you’re done. Pull the red probe out first, followed by the black probe. Handle them carefully so the metal tips don’t come into contact with one another. When you’re done, you can also detach them from the multimeter.
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Section 3 of 6:

Parts of a Multimeter

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1. 
   1
   Display The display is where you’ll see a reading of whatever you’re measuring (in this case, voltage). On an analog multimeter, the display will typically be a dial with a moving needle. On a digital multimeter, you’ll see a numerical reading.

   • You may see an On/Off button or switch somewhere on the body of the multimeter, but some automatically turn on and off, so don’t worry if you don’t see one on yours.
2. 
   2
   Selector Knob The selector knob is where you’ll choose the measurement you’re using. If you have a multimeter with an autorange feature, the selector knob may only have options for DC voltage, AC voltage, ohms, and resistance. If you have to manually select the range, you’ll see an array of numbers beside each unit of measurement.

   • For instance, next to DC voltage, you might see (from largest to smallest) 600, 200, 20, 2, and 200m (the m stands for milli, or 1/1000th).
3. 
   3
   Ports Multimeters typically have 2–4 ports. There’s always a common port (usually black and marked COM). This is where you plug in the black lead. If there’s only one other port, that’s where the red one goes.

   • Most often, there will be a total of 3 ports: the COM port, one marked with something like VΩmA, and one marked 10A MAX. You’d use the VΩmA for most projects and 10A for measuring higher levels of voltage, up to a maximum of 10 amps.
4. 
   4
   Probes Multimeters always come with a black probe and a red probe. The black probe is neutral, and the red probe is the one that carries the voltage to the meter to be measured.
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Section 4 of 6:

Measuring AC vs. DC Voltage

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1. 
   1
   Use DC to measure batteries, solar panels, and other small power sources. DC stands for direct current, meaning the waves of electricity flow in one direction. Batteries (including AA, AAA, 9V, and 12V) are all DC current, as are solar panels. Because most DC devices are relatively low voltage, it’s usually pretty safe to measure DC, but still make it a point to take all safety precautions (like not working in wet conditions).

   • “Around the house, most things will be AC unless they have a DC transformer, like some under-cabinet lights or low-voltage yard lights,” says Kuhlman.
   • “If the voltage is listed, it will specify AC or DC,” Kuhlman adds.
2. 
   2
   Use AC current if you’re measuring voltage in your home. AC stands for alternating current, meaning the waves of electricity alternate one way, then the other. “All of the electricity in your house is AC unless it has a transformer first,” says Kuhlman. That means if you’re measuring power to an outlet, you’d use AC.

   • Note that an AC current is often much stronger than a DC current, so be sure to use extra caution.
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Section 5 of 6:

Safety Precautions when Testing a Power Outlet

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1. 
   Take extra safety precautions if you’re testing a power outlet. In the US, household power outlets are 120V, which is more than strong enough to kill someone. If you’re not comfortable working with this type of electricity, don’t hesitate to call a professional. If you do decide to proceed, here are some safety tips to keep in mind:

   • Turn off the power first. Turn off the circuit breaker to that outlet before you get started to avoid a dangerous electrical shock. Or, if you live somewhere with electrical cutoff switches on the power outlets (like Great Britain), turn off the switch. (Note that this is not the same as turning off a light switch.)
   • Plug in a small device to double-check that the outlet is off. Plug in a lamp or another small electrical device to verify that the power is off to the outlet. Be sure to use something that you know is working.
   • Consider using a three-prong tester instead of a multimeter. “It’s easier to test an outlet with a three-prong tester,” Kuhlman advises. “It has three plugs on it, so you can just plug it into the outlet. The lights on the end of it will tell you exactly what’s going on, like if you’re missing a ground or the wiring is reversed.”
   • Plug the black prong into the neutral plug if you use a multimeter. “On a wall outlet, you have a longer side and a shorter side,” says Mitchell. “Put the black in the bigger side, and the red in the smaller slot on the outlet.” Insert the black plug first, then the red plug. You may have to push to get the prongs past the safety plate.
   • Turn on the power to the outlet. Once the multimeter is safely inserted into the outlet, turn on the breaker or power switch. Go back to the multimeter and check the reading, then turn the power off again. Do not touch the metal prongs while the power is on.
   • Remove the prongs from the outlet. Remove the red prong from the plug first, then the black plug. Then, unplug the red lead from the multimeter, followed by the black one.

Section 6 of 6:

Choosing a Multimeter

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1. 
   1
   Analog: Less expensive but harder to use Analog multimeters aren’t used much these days, mostly because it can be hard to get a precise reading from the dials. And although they’ve traditionally been less expensive than digital multimeters, there are plenty of low-cost digital options out there these days, making analog even less popular.

   • In some cases, analog multimeters may cost even more than digital options, probably because they’re less common.
2. 
   2
   Digital: More expensive but easier to use Digital multimeters do cost more than analog, especially if you get one with extra features like autorange. But basic digital multimeters are still pretty affordable, making them by far the more popular of the two options.
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Expert Q&A

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• Question

  When you test a broken fuse, what will it read on the multimeter?

  

  Ricardo Mitchell
  Electrician & Construction Professional, CN Coterie

  Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, OATH/ECB (Office of Administrative Trials and Hearings/Environmental Control Board) violations removal, and DOB (Department of Buildings) violations removal. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience.

  

  Ricardo Mitchell

  Electrician & Construction Professional, CN Coterie

  Expert Answer

  A circuit can't be completed when a fuse is broken, so it reads as an open line on the multimeter.

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Tips

• A non-functional multimeter could be because the device you are testing isn’t receiving power. Test other devices, such as nearby outlets, to ensure the power is on and the multimeter is working.
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• If you’re uncertain about performing a test or you detect anything unusual, contact an electrician for help.
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Warnings

• Working with live electrical circuits is dangerous, so perform tests with caution. Never touch live wires or outlets. Hold the multimeter probes by the plastic ends to avoid touching the exposed metal tips and short-circuiting the device.
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• Make sure you set the multimeter to test volts at the proper range. Using the wrong settings could damage the device!
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