Klein mm400 Review

Digital multimeters serve a wide range of functions for many hobbyists, professionals, and DIY-ers. But to find the perfect multimeter can be a tedious task. To make life easier, Klein offers a series of multimeters that are great quality but don’t break the bank. In this series, the mm400 is the simplest auto-ranging model. In this review, we’ll discuss who will get the most out of this multimeter, what it does, and why the Klein mm400 might be the perfect choice for more people than you might guess at a first glance!

Who is the Klein mm400 for?

The Klein mm400 is an excellent option for anyone who needs a good multimeter regularly, but whose job doesn’t depend on it. For DIY-ers around the house or hobbyists who work with household electronics or small electrical circuits, the Klein mm400 is a great general purpose digital multimeter.

For the professional electrician or someone who works with heavy equipment, the Klein mm400 will probably prove insufficient. At the same time, heavy-duty multimeters are not available in this price range at all. In this price range, the Klein mm400 packs a surprisingly powerful package!

Because of the auto-ranging functions of the mm400, this Klein model is a bit easier to use for the beginner and can also be faster to use if you switch functions a lot and don’t want to worry about deciding the correct range for each different measurement. The multimeter is CAT-III certified up to 600 Volt, and CE certified as well.

What’s included with the Klein mm400

The Klein mm400 is wrapped in a distinctive orange rubber case, which helps the multimeter survive drops from about 3 feet. The package includes two AAA batteries, very solid test leads, and a thermocouple with adapter that measures temperatures anywhere from 0⁰F to 1000⁰F. The slick design with just five buttons and the rugged gear-like knob that selects the main functions is a first indicator of its engineering quality.

When you take the Klein out of the package it comes in, you’ll immediately feel the quality as well. It is somewhat on the small side and fits neatly in one hand. The rubber casing and especially the ridges on the side help give you more grip, so it’s less likely to drop. If you happen to drop it outside or in a poorly-lit environment, the bright orange case will help you find it, too.

Klein mm400 Review


Klein Tools MM400 Multimeter, Digital Auto Ranging, AC/DC Voltage, Current, Capacitance, Frequency, Duty-Cycle, Diode, Continuity, Temp 600V

It carries out resistance tests up to 40MΩ, and duty-cycle, temperature, frequency, diode, capacitance, and continuity tests. The big 4000 count LCD display has a backlight, which will help anyone using the multimeter in cramped or darker conditions.

The battery compartment is easily accessible by unscrewing just one screw. On the other hand, replacing a blown fuse is a much bigger deal. To replace a fuse, you need to unscrew the entire back end of the multimeter (five screws in total).

Because the Klein mm400 is an auto-ranging multimeter, the tool looks minimalist and clean. Aside from the symbols and the maximum ranges for each function, the front of the multimeter is empty. It doesn’t just look nice, but also allows you to pick the correct function in the blink of an eye. Once you start a reading, the results show up quickly, which is a good feature and not a guarantee on an auto-ranging multimeter.

The Klein mm400 is a stripped-down version of Klein’s more extensive digital multimeters. It doesn’t have the same measurement range as its bigger brothers, and it only has a CAT-III rating, instead of the CAT-IV of the mm600 and mm700. These more extensive models also provide slightly better protection. But when it comes to the quality of engineering and the quality of the readings, the mm400 gives you the same excellent quality for a great price.

Klein mm400 Buying Guide

Alternatives for the Klein mm400

Klein Tools MM600

The mm400 is the ‘light version’ in Klein’s multimeter series. It still offers the auto-ranging function that is lacking on the mm300 but doesn’t come with the broad range and added durability options of the mm600 (check on Amazon.com) and mm700.

Other brands can compete with the Klein mm400 on price, but not on quality. Although Klein multimeters will always sit in the higher end of the price range, they’ll offer great readings and a long lifespan. People looking to buy a quality multimeter without having to buy a Fluke are best for buying a Klein.

If you’re considering a mm400 and feel it limits you too much in the measurements, but at the same time cannot afford a Fluke, the mm600 might just be what you need. You can read a review about the Klein mm600 here.


Klein offers a range of multimeters that give you great quality for a fair price. If you plan to use your multimeter regularly, but can’t justify buying the industrial standard, Klein will get you the next best thing. It offers good readings quickly, will last you decades, and can still offer excellent engineering for less than $50.

Download Klein MM400 Auto Ranging Digital Multimeter User Manual – Here!

Related posts about Klein MM400 Auto Ranging Digital Multimeter in Forums – Here!

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