The Accuracy of a multimeter is also known as Tolerance.


A tolerance can be expressed as a percent or in original units. 

For example, a ± 2% tolerance on 50 Volts could also be expressed as ± 1 Volt.

Also, the application of the Tolerance needs to be checked in the Handbook or Specifications for the meter as it could be applied to either:-

  • the actual reading, or
  • the maximum reading for the range selected

Example 1

A meter has a 1% tolerance. On the 100.0 ohm range a measurement taken is 50.0 ohms. 

1% of 100.0 ohms (the range) is 1 ohm, whereby 1% of 50.0 ohms (the reading) is 0.5 ohm.


Example 2

A meter has a tolerance of +/-1% of the FSD (100.0 ohms). The tolerance is therefore +/-1 ohm and the actual value can be between -1 and +1 of the measured value. If the reading is 50 ohms, the value can be anything between 49 and 51 ohms


Example 3

A meter has a tolerance of +/-1% of the reading (50.0 ohms). The tolerance is therefore +/-0.5 ohm and the actual value can be between -0.5 and +0.5 of the measured value. If the reading is 50 ohms, the value can be anything between 49.5 and 50.5 ohms


An additional tolerance for digital multimeters is "digit" accuracy. This is a number (as specified after the tolerance %) which alters the least significant digit by that amount.


Last modified: Monday, 5 June 2017, 9:16 PM