# Accuracy readings of a Fluke multimeter

Discussion in 'Electronic Basics' started by Jim, Jan 14, 2004.

1. ### JimGuest

Hi,

Can anyone explain the accuracy data of a multimeter specification.

I am looking at a Fluke 170 meter. The accuracy shown for the resistance is
+/- (0.9%+1) .

I understand the +/- bit, and I assume the percentage is a percentage of the

Any help appreciated.

Rgds

Jim

3. ### CFoley1064Guest

Hi, Jim. The accuracy specification for digital meters is frequently listed as
+/- percent of reading +/- number of digits or counts. So, your specification
means that, on that range, the meter is accurate to /- 0.9% of reading +/- 1
digit or count.

(By the way, I think the spec on the Fluke 179 and other 170 series meters is
+/- 0.09% rather than 0.9%. This is a *very* good handheld meter, if a little
pricey, and just about indestructible under normal use. 0.9% accuracy is
something you'd expect from one of the generic sub-\$30 knockoff meters.)

Let's say your spec is for DC Volts on a Fluke 179. So, if you read 10.00 VDC,
you are guaranteed accuracy of +/- 0.9% (+/- 0.09V) +/- 1 count (which would be
0.01V on that range). That would mean your maximum error would be +/- 0.10V.
In other words, the actual voltage could be anywhere between 9.9V and 10.1V.

If your Fluke 179 is rated for +/- 0.09% +/- 1 digit (the correct accuracy
(0.01V) +/- 1 digit (0.01V), or +/- 0.02V. You're guaranteed that the actual
voltage is between 9.98V and 10.02V. Big difference.

Hope this has been of help.

Good luck
Chris