I am using a multimeter that has an uncertainty (from the manual) of 0.5% plus 5 digits in DC voltage measurements, 4V range.

I have a reading of 1.6172 V. That means an uncertainty of 0.508 V. Isn't that way too much? Like the true value is between 1.1092 V and 2.1252 V. It seems odd to me such a big range of measurement. Or am I misinterpreting what 5 digits means?

Thank you

  • 1
    \$\begingroup\$ 5 digits is better described as 5 counts. Even then all your numbers come out of nowhere. I have no idea what you did. Show your calculations and what your interpretation of 5 digits is. Because I don't see anything close to 0.5% in there at all so it could be your interpretation is so far off that it is drowning out the 0.5%, or you also got the 0.5% wrong. \$\endgroup\$
    – DKNguyen
    Commented Dec 13, 2021 at 0:51
  • 1
    \$\begingroup\$ Granger, read the answers (both of them) for @TomC 's comment. You also didn't compute the 0.508 correctly. Here 0.5% means 0.005 (or 5 parts per thousand) times the reading. That is 8.08 mV, not 508 mV. About two orders of magnitude off the mark. As DKN says, the 5 digits should be read as 5 counts. So that's another 500 uV here. Add all that up and you get about 8.6 mV. (It may be worse. That's precision, not accuracy despite the fact that instrumentation will often state it as accuracy. To actually get accuracy, you'll need to find a traceable standard and use it appropriately.) \$\endgroup\$
    – jonk
    Commented Dec 13, 2021 at 1:09


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