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A Fast & Easy Guide on How to Calibrate a Multimeter

Multimeter getting calibrated-how to calibrate a multimeter

Technicians, electricians, HVAC and other professionals–and not to forget the home DIYer–all use multimeters to perform tests, troubleshoot and repair electrical issues. Multimeters, like all other electronics, need a reset every now and then. But if you think you can get away with never performing routine maintenance on your multimeter, nice try! Unfortunately, your favorite testing tool’s recalibration method is a little more involved than realigning your computer touch screen, but we’ll address everything you’ll need to know about how to calibrate a multimeter in the guide below. 

How to Calibrate a Multimeter

In order to recalibrate a professional-grade multimeter, you'll have to send it to the professionals. This isn't something that can be done at home simply because the machine required to do so would cost an arm and a leg to purchase. To prove this, the machine required to calibrate the Fluke 179 True-RMS digital multimeter costs over $45,000. 

Because they require advanced–and expensive–equipment to reset, it’s recommended that professional tradesmen send their multimeter to the lab for recalibration. For the basic DIYer, however, could get away with calibrating lower-grade multimeters with basic tools. Although, we still recommend sending them out to ensure personal safety.

Why Do We Calibrate Multimeters?

We calibrate multimeters because most manufacturers and calibrators only guarantee the device’s accuracy for up to 1 year. Multimeter calibration is especially important for those making critical measurements where the device's accuracy is as much a safety measure as it preserves its integrity as a diagnostic and troubleshooting tool.

Using measurements from an uncalibrated multimeter could lead to damage to equipment, employee health and company reputation. It’s also a legal obligation. Businesses must adhere to the multimeter’s calibration requirements or risk opening themselves up to lawsuits.

How Often Should Calibration Be Done?

You should calibrate your multimeter at least once a year to ensure that your device remains as accurate and as safe as possible. If you’re getting heavy use out of your DMM or making critical measurements, you should calibrate it once every three months. But that frequency can increase further if your multimeter experiences major stressors. These can include:

  • Humidity
  • Line voltage
  • Temperature fluctuations

For more information on the calibration specifications of your multimeter, you can reference the manufacturer's manual. 

Multimeter calibrator machine-how to calibrate a multimeter

How Much Does it Cost to Calibrate a Multimeter?

It will run you anywhere from $90-$400 to send your multimeter into the lab for calibration. Factors that impact pricing will depend on a few factors such as:

  • Type
  • Model
  • Features
  • Brand
  • Complexity of your multimeter

How Do I Test if My Multimeter Is Accurate?

So you know how often a multimeter needs to be calibrated, but how do you know if it’s working properly in between maintenance stints? There are a few ways to test this. For example, you can compare your multimeter’s voltage results against a power source with a known DC and AC voltage, such as a 9-volt battery or a 120-volt house socket. However, to fully test the accuracy of your multimeter, you’ll have to repeat this process with each function and its corresponding ranges. 

It’s also a good idea to check your multimeter’s accuracy range. For example, if the basic DC accuracy is published as 1%, it means the value shown on the screen will be within a standard deviation range of 1%. So if you set your multimeter to the 0-100 volt range to measure a known power source of 15 volts, your multimeter might read it as a value between 14-16 volts. If the results are outside this range, then you should send your multimeter in for calibration.

That said, multimeters are a safety device, so when in doubt, send it in. If you have any further questions about how to test wires for voltage or how to use multimeters, please check out these articles. 

How Do I Choose a Multimeter Calibrator?

When it does come time to calibrate your multimeter, there are a few things you should look for. For one, you should send it to an accredited calibration lab. An accredited lab is regularly audited by a third party to ensure it meets international standards. But depending on your company policy or whether you’re in an industry that must meet ISO or IEC requirements, you might need an accredited calibration or traceable calibration for legal reasons. 

Sometimes you can send it back to the manufacturer for calibration. For example, Fluke owns an accredited lab and performs its own calibrations. However, this is not always possible, especially for brands that produce cost-conscious multimeters.