Handheld Multimeter Buying Guide

The digital multimeter is undoubtedly the most commonly used measuring tool in the field of electrical engineering and electronics. In keeping with their popularity, the selection of models is wide. This guide will help you make the right choice for your application.

Multimeter general purpose

Multimeters are used to measure basic electrical quantities of current, voltage (AC+DC) and resistance. This versatility earned them their names: 'multi' (=many) 'meter' (=measuring). Most multimeters also allow you to measure additional quantities, such as capacitance, frequency, or temperature. At its core, a multimeter is a compact and versatile tool.

The customary term "digital multimeter" comes from the tool's method of measurement, rather than its numerical display. Almost all multimeters use a digital measurement method, which means that the initial analog data collected is converted into a digital signal and further processed by an AD converter integrated into the multimeter. Features such as autoranging or controlling digital displays establish the requirement for digital information. Even so, a digital multimeter with an analog display is an option—these devices display readings on an analog bar graph or as an analog meter.

How to use a digital multimeter?

If you already know the primary purpose of a multimeter, be sure to consider the setup and approach before starting any of your applications (monitoring, analysis, troubleshooting, or inspection). Common ones include:

Set the correct measurement accuracy and resolution.

Measure the current through a circuit.

Test the diode.

Measure the frequency of AC signals.

Check the capacitor value.

Test switches, connectors, and fuses for continuity.

measure temperature.

Accuracy and resolution

When choosing between different models, the measurement accuracy of your multimeter may be the deciding factor. For example, accurately matching the voltage of a circuit requires higher voltage accuracy than general electrical testing.

Accuracy can be measured as a percentage, taken from the final value or measured value of a set measurement range. The difference between the two is considerable, and it would be wise to consult the data sheet to determine the advertised value of your multimeter. As a rule of thumb, AC measurements are much less accurate than DC measurements.

Resolution is defined as the smallest difference in measurements that a multimeter can recognize. For different measurement ranges, the multimeter will have different resolutions. Typically, the resolution is high enough to provide good results within the basic accuracy range.

price range

There are a variety of multimeters available for purchase, so the price range may vary as well. Enthusiasts may be looking for the limited functionality available in basic multimeters, with prices ranging from €10 to €100. Cheaper multimeters have a sampling rate of two per second, which is usually not high enough for professional applications. Low prices for professionals start at €100. Prices range from 200 to 500 euros for mid-range professional products and 500 to 1500 euros for high-end multimeters - their high specifications justifying the high price tags.

Additional features

The real differences between multimeters start to appear when we get into the list of additional features available, beyond the most basic capabilities of measuring current, voltage, and resistance. With some multimeters, you can also test capacitance, frequency, continuity, diodes, and duty cycle. We’ve put together some additional features a multimeter can offer that may influence your buying decision:

true valid value

Measuring non-sinusoidal alternating current requires a multimeter with true rms capability. Some examples of environments that require true rms instruments include variable speed motor drives, electronic ballasts, computers, HVAC, and solid state environments. Uneven AC voltage or current can only be measured correctly with a TRMS multimeter. A simple RMS multimeter always assumes that the AC voltage being measured is a sine wave - the reading is calculated as the mathematical average of this perceived sine wave. This method does not work with AM or FM AC and requires a TRMS multimeter to obtain an accurate reading.

Check out the RND unboxing video to learn how the True RMS auto-ranging digital multimeter works and how to use it.

Security Level

The safety of a multimeter is an important factor that will undoubtedly influence your decision on which one to buy. Every multimeter will fall into one of four security classes:

Category I: For measurements performed on circuits not directly connected to MAINS, such as small electronic projects.

Category II: For measurements performed in circuits directly connected to low-voltage installations such as household appliances or portable tools.

Category III: For measurements performed in building installations such as switchboards, circuit breakers, wiring, busbars, junction boxes, switches, socket-outlets in fixed installations and industrial equipment.

Category IV: For measurements made at the source of low-voltage installations, such as electricity meters and primary overcurrent protective devices and ripple control units.

Keeping the multimeter's intended use in mind, it's easy to determine which level of safety your equipment requires. If you suspect that you may be using your multimeter to measure higher voltages in the future, it is recommended to select a higher category safety rating.

Precision desktop multimeter

In the field of research and development, the need for particularly high measurement accuracy sometimes arises – especially when working with extremely low currents and voltages. This is where precision bench multimeters shine: they can measure currents down to nanoamps. In addition to extremely high accuracy and resolution, these devices often feature programming capabilities, data logging or graphical displays.