Klein MM400 vs MM420 – Choosing the Best Fit

DANIEL FOSTER

As an electrical engineer from Stanford University with over 7 years of experience using multimeters.

Regarding multimeters, Klein is a brand that’s no stranger to the game. They’ve built a solid reputation for themselves in electrical tools and equipment. But let’s focus on the stars of the show: the MM400 vs MM420 multimeters. These bad boys are not only reliable, but they also won’t break the bank. Yep, they’re two of the most budget-friendly options out there.

Based on my experience and expertise in this field, let’s delve into what sets these two multimeters apart in this comparison. 

Let’s get this comparison show on the road!

Klein MM400 vs MM420 – Which One to Consider?

The MM400 offers auto-ranging and a wide voltage range, while the MM420 adds True RMS and increased durability. Based on my research and opinion, the MM420 is more affordable and has added features. Additionally, user feedback leans towards the MM420.

Klein MM400 vs MM420 – Specifications Table

Let’s start by taking a look at the specifications of the Klein MM400 and MM420 multimeters side by side.

FeatureKlein MM400Klein MM420
Display4000-count LCD4000-count LCD
True RMSNoYes
Voltage Range0.1mV – 600V0.1mV – 600V
Current Range0.1μA – 10A0.1μA – 10A
Resistance Range0.1Ω – 40MΩ0.1Ω – 50MΩ
Capacitance Range1nF – 200μF1nF – 400μF
Frequency Range1Hz – 50 KHz1Hz – 50 KHz
Duty CycleYesYes
Temperature Range0°F to 1000°F(-18° – 538°C)-40° to 1832°F (-40° to 1000°C)
Diode TestYesYes
Continuity TestYesYes
Low Battery IndicationYesYes
Safety RatingsCAT III 600VCAT III 600V
Drop Protection3.3 ft (1m)6.6 ft (2m)
Auto-RangeYesYes
PriceHigherLower

Klein MM400 – Quick Rundown

Features

  • Measures up to 600V AC/DC voltage
  • Electrical tester: temperature, capacitance, frequency, duty-cycle
  • CAT III 600V safety rating
  • Withstands a 3.3-foot (1 m) drop
  • Low battery indicator
  • Suitable for light-industrial locations

Alright, let’s jump right into the Klein MM400! 

The Klein MM400 is an auto-ranging multimeter that offers a 4000-count LCD display, providing clear and precise readings. It covers a wide range of measurements, including AC/DC voltage, AC/DC current, resistance, capacitance, frequency, duty cycle, diodes, and continuity.

While the MM400 lacks True RMS measurement capability, it is still a reliable tool for everyday electrical measurements.

When it comes to durability, the MM400 doesn’t disappoint. It is designed to withstand drops of up to 3.3 feet (1 meter), ensuring it can handle accidental slips or falls in typical work environments.

Overall, the Klein MM400 is a reliable and feature-packed multimeter suitable for both professionals and DIY enthusiasts who require auto-ranging capabilities but not require True RMS feature.

The package for the Klein MM400 includes:

  • Klein MM400
  • Test leads
  • Thermocouple with adapter
  • Batteries
  • User manual

Pros

  • Trusted brand for quality
  • Compact design
  • Clear display with backlight
  • Auto-ranging
  • Includes capacitance, frequency, and temperature inputs
  • Supple leads

Cons

  • Not True RMS
  • No case included

Klein MM420 – Quick Rundown

Features

  • Measures up to 600V AC/DC voltage
  • Electrical tester: temperature, capacitance, frequency, duty-cycle
  • CAT III 600V safety rating
  • Withstands a 3.3-foot (1 m) drop
  • Low battery indicator
  • Suitable for light-industrial locations

Now, let’s shift our focus to the Klein MM420. The Klein MM420 shares many similarities with the MM400 but offers some key improvements.

Like the MM400, the MM420 is an auto-ranging multimeter. It also features a 4000-count LCD display and auto-ranging capability. However, the MM420 stands out with its True RMS measurement capability.

The resistance range of the MM420 is expanded to 50MΩ, providing more comprehensive resistance measurements compared to the MM400’s 40MΩ range. This is advantageous for professionals working with a wide range of electrical components.

Additionally, the MM420 provides improved drop protection, withstanding falls from 6.6 feet (2 meters). This enhanced durability makes it ideal for demanding work environments where accidents are more likely to occur.

With its auto-ranging capabilities, True RMS measurement, extended resistance and temperature ranges, and improved drop protection, the Klein MM420 is a solid choice for professionals who require an affordable versatile multimeter.

The package for the Klein MM420 includes:

  • Klein MM420
  • Test leads
  • Thermocouple with adapter
  • Batteries
  • User manual

Pros

  • Trusted brand for quality
  • True RMS
  • Compact design
  • Clear display with backlight
  • Auto-ranging
  • Includes capacitance, frequency, and temperature inputs
  • Supple leads 
  • Comes with a thermocouple
  • Affordable price point

Cons

  • No case included

What Users Say About Klein MM400 and MM420

Customers who have used both the Klein MM400 and MM420 have shared their experiences and opinions. 

Starting with the Klein MM400, often praised for its versatility, clear display, and reliable performance. Users appreciate the added temperature measurement feature and the durable construction. The MM400 is often regarded as a significant upgrade from lower-priced multimeters available in the market.

Moving on to the Klein MM420, users highlight its auto-ranging functionality, expanded resistance and temperature ranges, and improved drop protection. The True RMS capability receives positive feedback for providing accurate measurements, even in challenging electrical environments. 

Users find the MM420 to be a reliable and professional-grade multimeter that meets their expectations in terms of performance and durability.

Final Verdict – MM400 vs MM420

In the final verdict of the MM400 vs MM420 face-off.

The MM420 offers enhanced features such as True RMS measurement, extended resistance and temperature ranges, and improved drop protection. It is a versatile and professional-grade multimeter that caters to the needs of electricians and other professionals.

On the other hand, the MM400 remains an excellent choice if you don’t require the higher resistance and temperature ranges. It provides reliable performance, True RMS measurement, and auto-ranging convenience.

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