Introduction: How to Use (and Choose) a Multimeter!

Checking your car battery life, debugging circuits, and finding that pesky short are all super useful functions that can be done with just one awesome tool: the multimeter!

First of all, what the heck is a multimeter?? Excellent setup question! It's a handheld device with bunch of different electrical meters -- hence, multi-meter!

Measuring voltage, current, resistance, and continuity (aka electrical connection) are the most common uses of a multimeter. Read on (and/or check out the videos) to learn what this means, how to do it yourself, and how to choose your very own multimeter!

Step 1: Choosing a Multimeter!

Picture of Choosing a Multimeter!

There are a few key differences between multimeters, the main one being analog versus digital:

Analog multimeters show real-time changes in voltage and current, but can be difficult to read and log data.

Digital Multimeters are easier to read, but may take some time to stabilize.

There are also auto-ranging multimeters, that automatically detect the measurement range, and manual ranging multimeters where you have to choose a range yourself (or start with the highest setting and work down).

Other than those two main differences, you'll want a multimeter that has separate ports for current and voltage measurements (this is a safety issue, both for the meter and for yourself).

Next comes the fun part: features! All multimeters have voltage and current meters (otherwise they'd just be called voltmeters and ammeters!), and most also measure resistance. There are a variety of other "extra" features depending on manufacturer and cost (e.g. continuity, capacitance, frequency, etc.).

Second-to-lastly, there are a ton of different types of probe leads, including alligator clips, IC hooks, and test probes. Can't decide? Here's a kit that has four different types!

Lastly, always check the multimeter maximum voltage and current ratings to be sure that it can handle what you want to use it for.

Step 2: Measuring Voltage!

Picture of Measuring Voltage!

A voltage measurement tells us the electrical potential, or pressure, across a particular component.

Voltage is basically the "oomph" in our circuit, so we want to avoid drawing any power from the circuit when we take a voltage measurement. This means we need to measure voltage in parallel with a particular component using infinite (or really, really high) resistance.

Using a multimeter to measure voltage across a component (or battery):

1. The black multimeter probe goes into the COM port, and the red probe into the port marked with a "V".

2. Switch the dial to the "voltage" setting (choose the highest setting if you have a manual ranging multimeter).

3. Place black probe on negative side of the component, and red probe on positive side (across, or in parallel with the component). If you get a negative reading, switch the leads (or just note the magnitude of the voltage reading).

Read the meter output and you're done! Not too bad :)

Step 3: Measuring Current!

Picture of Measuring Current!

Taking a current measurement tells us the amount of electricity flowing through a given component or part of a circuit.

To measure current, we want to measure all of the electrons flowing in our circuit. This means we measure current in series with a component using zero (or negligible) resistance.

Using a multimeter to measure current through a component:

1. The black multimeter probe goes into the COM port, and the red probe into the port marked with an "I" or an "A" (or "Amp").

2. Switch dial to the current setting (choose highest setting if you have a manual ranging multimeter).

3. Connect red probe to current source, and black probe to the input of the component, so that the current flows from the source, through the meter, to the component (in series with the component).

Read the meter output! If you're not getting a reading, switch to a lower setting.

Step 4: Measuring Resistance!

Picture of Measuring Resistance!

Measuring resistance is similar to measuring voltage, the biggest difference is that you have to disconnect the component from the circuit (otherwise the other circuit components interfere with your measurement).

Using the multimeter to measure resistance of a component:

1. Put the black probe in COM port, and red probe in the port marked with a "Ω" or "Ohm" -- it should be the same port as the voltage port.

2. Switch dial to setting marked with a "Ω" (may have to choose approximate range for manual ranging multimeter).

3. Place probes on either side of the component (orientation doesn't matter).

Read the meter output and you have conquered resistance!

Step 5: Bonus: Measure Continuity!

Picture of Bonus: Measure Continuity!

The continuity measurement checks if two points in a circuit are electrically connected, otherwise known as a conductance test. Before measuring continuity, be sure that the circuit power is OFF.

Using the multimeter to measure continuity:

1. Place black probe in COM port, and red probe in voltage port.

2. Switch dial to setting marked with an audio symbol.

3. Place probes at points you want to check -- if the meter makes a beep sound, it means the two points are connected.

Le fin!

Step 6: Go Forth and Measure All the Things!

Picture of Go Forth and Measure All the Things!

Now that we know how to use a multimeter, get crackin' on all those at home, DIY projects!

To get you started, here are a few quick, practical, & fun projects:

1. Measure the resistance of your skin! Change the distance of the probe leads and see how resistance changes. Lick your fingers (or dip them in water) to see how moisture affects resistance!

2.Use the continuity setting to check if different materials conduct electricity.

3. Make a lemon battery and measure the voltage and current output.

4. Use the continuity setting to check if different materials conduct electricity.


yizahkJamesLafter (author)2016-06-30

Am a student learing Electronics and i appreciate the guide on how to use my miltimeter. Thanks

Awesome, glad you found it helpful!

Hey friend,

Do you like Electronics and Science Technology too?

What are you doing???

XirxiousC (author)2016-06-15

If you get the Harbor Freight flyers, they often have coupons for a free meter. Its a lower end model, but its free!

jenfoxbot (author)XirxiousC2016-06-16

Ohh that's very good to know, thank you!!

donfrench (author)2016-06-10

There are two other features of a multi-meter that are indispensable in my opinion.

First is a built-in support on the back so that you can tip the thing up to almost vertical. This is so you can read it when it is impossible to have it directly beneath your eyes. If the meter has a light-emitting display this isn't so important but most don't in my experience. I just bought a DVM that has a back that folds out from the top so it would have been ideal in this respect if they had only put a stop on it to prevent it from falling over.

Second is auto-turn off. If you don't have this your batteries will need recharging or replacing much, much sooner because we all forget to turn these things off.

Actually, there is a third feature that relates to the second one. The required battery or batteries should be the kind that are rechargeable. AA's or AAA's or even a standard 9V.

The DVM I mentioned in feature one was a fail on all three points. It couldn't stand on its own. It remained on until I manually turn it off. And the required battery is one of those stubby 9V's that don't come in rechargeable form. But I needed one in an emergency and it was only $24.95 at Radio Shack.

jenfoxbot (author)donfrench2016-06-14

Great additional information! Have definitely left my meter on more than once..

0zzy (author)2016-06-11

Very nice and helpful thanks
And yes I would love for you to make an insatiable on a oscilloscope I have got one that I was given but I haven't a clue how to use it so yes please can you make one
thanks and I look forward to see and read that one

jenfoxbot (author)0zzy2016-06-14

Glad you found it helpful! Working on a tutorial + video for an oscilloscope, stay tuned!

UncleEd (author)2016-06-07

Very useful instructable.

A suggestion that reflects my status as a cheapskate: find another multimeter cheap enough that you won't cry if you lose it or drop it. If you go somewhere and it's raining or rough terrain, unless you REALLY need certain features, the meter from the cheap tool store giveaway will be plenty good.

jenfoxbot (author)UncleEd2016-06-07

Thanks! Also thanks for the tip -- as long as high voltage/current are avoided a cheap meter is probably just fine.

AlM47 (author)jenfoxbot2016-06-08

I don't think Uncle Ed was saying a cheap meter is just fine. He uses a more expensive meter but gets a second cheapie for rough/risky jobs.

UncleEd (author)AlM472016-06-08

We can say I would use an expensive nice meter. One of the leads on the good meter was caught under something, when I picked it up. The lead held and my hand didn't and the meter hit the concrete floor. I didn't cry, but I was disappointed.

The cheap digital meter from my toolbox will tell me if a 5VDC power supply is pretty close to 5V. The 10A scale has awful absolute accuracy but will tell me which flashlight cells are good enough to keep and which to throw away or recycle. It can tell if a wall socket is live and about the right voltage.

(Checking the same battery on two cheap meters on the 10A scale makes me guess neither is a good number. The lower current scales are pretty good, though.)

A Kickstarter here at home to replace the good meter...not likely, I guess.

jenfoxbot (author)UncleEd2016-06-08

Aw, dang, that sucks about your good meter! The really nice ones definitely get quite pricey.. sounds like you know what you're doing so hopefully the inexpensive ones suffice for now.

Also, try checking e-bay. Occasionally there are some older models that are still just fine and that are waay cheaper than the new ones.

jenfoxbot (author)AlM472016-06-08

Sounds like you know uncle ed!

fencer (author)2016-06-07

AC is more dangerous

jenfoxbot (author)fencer2016-06-07

Technically, when everything is the same, high voltage DC is more dangerous because it causes your muscles to contract so you can't let go. Although, of course, all high voltage and high current is dangerous so be careful regardless!

UncleEd (author)jenfoxbot2016-06-08

Yet another minority report--it's a challenge to find ANY voltage, AC or DC, that cannot possibly be dangerous. In an early Electronics class, the professor told us if someone wanted to go in the worst way, he could do it using a little wire and the flashlight cells you could hold in one hand. No transistors, ICs, capacitors, coils, or anything. It would not be pleasant at all, but dead is dead.

The point is to not get your body "involved" in an electric circuit. Yes, it's more convenient to get damaged by higher voltages and there are some academic distinctions between AC and DC, but proper care and behavior are essential. Thomas Edison's group spent a lot of money trying to convince the public that the AC advocated by George Westinghouse was dangerous and the DC his company was selling was less dangerous. The history is interesting, but the actual difference in "dangerousness" is irrelevant.

The takeaway is to be careful and know what you're doing.

jenfoxbot (author)UncleEd2016-06-08

Yes, absolutely, agree with you 100% on that. Regardless of AC or DC distinction, any voltages above 20V and currents above 100 mA should be treated with extreme caution. Double and triple check things, and always use the one hand rule!

Fezder (author)fencer2016-06-07

In case someone wonders why, this is because alternating current interferes with heartbeat (if current goes through heart, can cause ventricular fibrillation (heart tries to beat too fast, blood won't pump in veins pretty much at all)

) and it causes muscles to stiff so brains commands won't do pretty much a thing when you try to command your muscles. What else? Oh, and zap from ac feels awful....But, DC also has hazards, like charged capacitor, enough big energy and those are deadly as well, plus other places too. I might got few terms/facts bit wrong, but this is main princible.

jenfoxbot (author)Fezder2016-06-07

Ah actually DC is more dangerous, assuming that the RMS of the AC is ~ max DC (since DC causes your muscles to contract and you can't let go, whereas with AC you have a fraction of a second where the voltage is zero so you'll be able to release). Of course, both are very dangerous and can be extremely painful, so caution is essential with any high voltage or current. One hand rule every time!

Fezder (author)jenfoxbot2016-06-08

Hmm, true. Found nice article on subject:

AlM47 (author)2016-06-08

Not sure what is going on here about measuring open circuit battery voltages to check a battery's state of charge. With AA & other small batteries as far as I know the voltage MUST be checked under load. When I pull out a handful of good AAs of different types and charge levels as checked on my Radio Shack battery tester (that tests through a resistor) that I've used for thousands of cells over decades, it shows the cells to be at all different levels. When I test the voltage on my multimeter it shows all the Alkaline and 1.5 +/- .02 and all the regchargables at 1.2 +/- .04. However if I test on the 10A scale (which I think has a resistor for load) they all vary in sync with the Radio Shack battery tester. That's what I thought and others here have said the same. I think the video needs to be amended because it seems to be misleading people on this subject.

jenfoxbot (author)AlM472016-06-08

Checking the battery open source voltage ("OSV") is a quick way to (roughly) estimate the lifetime of the battery. A fully charged battery should have a higher OSV than the manufacturer rating (e.g. 9V typically float between 9 and 10 V). If you check the OSV of a battery and it is below the manufacturer rating (e.g. a 9V shows a 7V reading), then you know the battery is dead/dying.

Of course, if you want to check the operational battery voltage you need to measure it under load. Hope that helps clear things up for ya!

Fezder (author)2016-06-08

Can you make similar for oscilloscopes? :)

jenfoxbot (author)Fezder2016-06-08

You read my mind!!

privatier (author)2016-06-07

When measuring current, the current flows through a resistor inside of the multimeter, and the instrument actually measures the voltage across, which is proportional to the current. The internal resistance should be small, in order to have a small influence on the behaviour of the circuit which you want to measure. Consider that some auto-ranging meters have a relatively high resistance, with voltages across the instrument terminals approaching 1V at full scale.

When measuring small resistance, on the order of 1Ohm, consider the resistance of the probes. Short the tips to read the resistance of the leads, and subtract this value from the one displayed when connected to the resistor under test.

maniacse (author)privatier2016-06-07

Exactly, I always use this also before continuity test (my meters do not have function of displaying "Open/Close", I just have beepin'). Just to be sure that everything is working fine and I can rely on test/measuring results.

t.rohner (author)maniacse2016-06-07

For measuring really small resistance, there is also a so called 4 point measurment. One set of probes supplies the current over the resistor under test, the other set measures the voltage over it. Thus eliminating the resistance of the measuring probes. (This feature is normally found in benchtop meters, not in handhelds)

jenfoxbot (author)privatier2016-06-07

Thanks for the additional info! Pretty crazy how much of a difference probes can make, or the length of the wire!

SherpaDoug (author)2016-06-07

Auto-ranging meters tend to be very slow. I won't buy a meter where auto-ranging can't be disabled.

jenfoxbot (author)SherpaDoug2016-06-07

Ah yup, gotta have some patience with those auto-ranging meters!

VládaB (author)2016-06-07

For better measured value of resistance i recommend hold first measuring tip of multimeter in the fingers with a resistor and second measuring tip of multimeter only attach to a resistor pin without a fingers - body resistance may be manipulate of measured values ! :-) (good tip from practise)

jenfoxbot (author)VládaB2016-06-07

Thanks for the tip! Those little things can make a huuuge difference!

shadders (author)2016-06-07

Another point to consider when selecting a
multimeter and working with AC circuits is whether you need a true RMS
meter. A lot of the cheaper models aren't true RMS capable. See the link
below from a reputable manufacturer (my preferred one).

jenfoxbot (author)shadders2016-06-07

Great point! Thanks for adding the link. Also, fluke meters rule.

Fezder (author)2016-06-07

couple things to add if you don't mind: not all multimeters have fuse in higher-amp side, safety issue(some meters have sliding doors in front of amperage/voltage sockets, which prevent "faulty" connections, but of course stuff can happen). Other think I could think of is overall speed so you don't need to wait ridicilously long times in case you're pondering with connections. And about test leads, get some silicone/rubber ones. Much more convenient to use. To test whether your leads are anywhere close to silicone/rubber, too 'em in freezer. If they're stiff after (place time here, 2hrs?) they're not rubber......and please don't measure how much current comes from wall socket! I have few EE-student fellows who did this... Good 'ible before I forget! :D

jenfoxbot (author)Fezder2016-06-07

Thanks! Ha yea there's always more to learn about multimeters! They are a great introductory tool but you can also get reaaaaally deep into them.

billbillt (author)2016-06-07

Thanks for sharing this... It is very important info well written in a manner understandable by anyone,,,

jenfoxbot (author)billbillt2016-06-07

Thank you!! :D

magkopian (author)2016-06-07

Nice instructable, I think no beginner should have an issue understanding it the way you explain it. I'd like though to add one thing regarding the way you measure the battery voltage. I'm not saying that the way you are doing it is wrong, but I think you should be aware that what you are measuring is the open circuit voltage of the battery and in many cases this may not the what you want. Please let me explain what I mean by that.

Batteries have an internal resistance which is going to cause a voltage drop as soon as you connect them to a circuit that draws an amount of current, and the larger the current the bigger the voltage drop will be. What I mean is that you may initially measure 8V for example on a 9V battery while in open circuit, but as soon as you connect it to your circuit the voltage may drop to less than 7V, in case it happens for it to draw a relatively high amount of current. And then keep wondering why your circuit is not working even though it only requires a minimum of 7V to work the moment you measured 8V.

Measuring the voltage of a battery while in open circuit may give you a rough idea about the state of the battery, but usually the best way to do it is by measuring the voltage with the battery connected to your circuit and check if the voltage level is above the minimum required from your circuit to operate. Please excuse me if you already know this stuff, but as someone who did a lot that mistake in the past I hoped that you (or someone else who reads it) may find it useful.

jenfoxbot (author)magkopian2016-06-07

Thanks for the comment and helpful info! You are absolutely correct -- measuring the voltage across a battery is measuring the open circuit voltage, which is typically higher than the manufacturers rating unless it's dying/dead, which is a good way to check the life of a battery!. I think I mention this issue in Part 2 of the video when I get the car battery voltage (although I might've edited it out for the sake of time). Definitely helpful information to know!

ccray1954 (author)2016-06-07

i have a Multimeter coming thru the mail soon and i needed to know how to use it for my cb antenna continuity. just one look at your film i was schooled. thank you for this..great film very informative!

MarkF96 (author)ccray19542016-06-07

Hey bud what u need is a swr meter. The multimeter is indispensable for any project. The antenna will need to be tuned for that u will use the standing wave ratio (swr) meter. Here's an idea get a ham radio operator license. Way way more fun

AB1BE (author)2016-06-02

Martin Lorton has a site with a lot of excellent knowledge about choosing and using multimeters.

jenfoxbot (author)AB1BE2016-06-02

Cool! Looks like an interesting site!

aeroman2010 (author)2016-05-30

Thanks for valuable information

jenfoxbot (author)aeroman20102016-05-30

Absolutely! Hope it helps w/ future projects!

Dlhornscxm (author)2016-05-28

Great information and breakdown of the steps involved. This has always been kind of a mystery to me. I now have a little confidence in this department. Thank you very much.

jenfoxbot (author)Dlhornscxm2016-05-30

Thank you!! Very happy that it helped you w/ multimeters, they are a really awesome + handy tool!

About This Instructable




Bio: Dabbled in dark matter, settled into engineering with a blend of inventing and teaching, always trying to solve problems + learn new things!
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