Input Impedance on Multimeters and Clamp Meters

The input impedance of a product is not always easy to find! Many DMMs have them listed in the specifications, but for Clamp Meters this information is not typically a matter of record.

This list was gathered in May of 2025. Newer products maybe not have been added to the listed yet.

Digital Multimeters

The following values were gathered by checking each meter's specifications.

Fluke 83V - 10 MΩ, includes High Impedance
Fluke 87V MAX - 10 MΩ, includes High Impedance Mode
Fluke 88V - 10 MΩ, includes High Impedance Mode
Fluke 15B+ - 1 MΩ AC & DC mV range, 10MΩ using other ranges for AC & DC Volts                                                                                                                Fluke 17B+ - 1 MΩ AC & DC mV range, 10MΩ using other ranges for AC & DC Volts
Fluke 110 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ mode
Fluke 113 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ and VCheck Mode
Fluke 114 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ mode
Fluke 115 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ mode
Fluke 116 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ mode
Fluke 117 - 5 MΩ AC, 10 MΩ DC, 3 kΩ on Auto-V LoZ mode
Fluke 175 - 10 MΩ
Fluke 177 - 10 MΩ
Fluke 179 - 10 MΩ
Fluke 27 II - 10 MΩ
Fluke 28 II - 10 MΩ
Fluke 28 II EX - 10 MΩ
Fluke 279 FC - 10 MΩ                                                                                                                                                                                                                      Fluke 283 FC - 10MΩ
Fluke 287 - 10 MΩ, 3.2 kΩ on LoZ VAC mode
Fluke 289 - 10 MΩ, 3.2 kΩ on LoZ VAC mode
Fluke 3000 FC - 10 MΩ
Fluke 1577 - 10 MΩ
Fluke 1587 - 10 MΩ
 

Clamp Meters

The following values were gathered in-person by measuring with an 87V.

Fluke 301D - 1 MΩ
Fluke 302+ - 10 MΩ on DC, High Impedance on AC
Fluke 323 - 10 MΩ on DC, High Impedance on AC
Fluke 325 - 1 MΩ
Fluke 365 - 1 MΩ
Fluke 373 - 1.5 MΩ
Fluke 374 FC - 1 MΩ
Fluke 375 FC - 1 MΩ
Fluke 376 FC - 1 MΩ
Fluke 377 FC - 1 MΩ
Fluke 378 FC - 1 MΩ
Fluke 381 - 1 MΩ
Fluke 393 FC - 1.35 MΩ
​​​​​​​Fluke 902 FC - 1 MΩ
​​​​​​​Fluke 355 - 2.5 MΩ

​​​​Legacy Digital Multimeters

The following multimeters are no longer manufactured, but specifications were found and gathered here.

Fluke 233 - 5 MΩ AC, 10 MΩ DC
Fluke 27 – 10 MΩ
Fluke 87 – 10 MΩ
Fluke 87III - 10 MΩ
Fluke 87IV - 10 MΩ
Fluke 89IV - 10 MΩ
Fluke 187 - 10 MΩ
Fluke 189 - 10 MΩ
Fluke 867B – V AC - 1.11 MΩ ±1% in series with 0.1 µF, V DC -10 M Ω, mV DC - 10 M Ω, mV DC Hi-Z - >1000 M Ω

Legacy Clamp Meters

The following multimeters are no longer manufactured, but remaining examples around the office were tested and gathered here.

Fluke 303 - 10 MΩ on DC, over 500 MΩ on AC
Fluke 319 - 1 MΩ
Fluke 321 - 1 MΩ
Fluke 322 - 1 MΩ
Fluke 334 - 1 MΩ
Fluke 337 - 1 MΩ

Note on High Impedance Modes

High Impedance Modes are considered "undefined" by Fluke engineers. Suffice to say, this mode provides an input impedance of at least over 500 MΩ for our clamp meters and estimated to be on the order of GΩ for digital multimeters.

Note on Capacitance in Impedance Specifications

Input Impedance is often listed alongside a capacitance value, such as 100 pF in the example below.

Capacitance is one of the complex components of Impedance. This specification means that a measurement of the ports will appear like a 10 MΩ resistor with a parallel capacitor of not more than 100 pF.