How to use this multimeter accuracy calculator

1. Choose the same accuracy specification format shown in your multimeter’s manual. If you need to find the documentation, start with our multimeter user manual collection.
2. Enter the number currently displayed by the meter and select its measurement unit. For a refresher on ranges and measurement modes, see our multimeter basics guide.
3. Enter the accuracy percentage specified for that measurement function and range.
4. For a + counts specification, enter the added counts and the resolution of the active range. For % of range, enter the range span given in the specification.
5. Read the maximum specified error, possible measurement interval, and full breakdown.

Understanding the accuracy formula

Digital multimeter accuracy is commonly stated as ±(% of reading + digits/counts). The percentage term changes with the reading. The counts term is the number of least-significant display counts multiplied by the resolution of the selected range. Those values are added to determine the stated absolute error limit.

Example: For 12.50 V, 0.5% of reading is 0.0625 V. Two counts at 0.01 V each contribute another 0.02 V. The total specified error is ±0.0825 V, giving an interval of 12.4175–12.5825 V.

Some advanced meters instead quote a percentage of the measurement range. Always use the specification format for your particular meter; do not confuse % of reading with % of range. If you are new to taking readings, our guide to using a multimeter covers basic measurement functions.

Important limitations

The result assumes that the displayed reading, accuracy terms, and range resolution are provided in the same unit. It also assumes the meter is operating within the conditions required by its manufacturer. Temperature coefficients, AC frequency, crest factor, probe error, calibration status and other conditions can create additional errors. A calculator cannot prove a meter is safe or properly calibrated.