Resolution may be listed in a meter’s specifications as maximum resolution, which is the smallest value that can be discerned on the meter’s lowest range setting.įor example, a maximum resolution of 100 mV (0.1 V) means that when the multimeter’s range is set to measure the highest possible voltage, the voltage will be displayed to the nearest tenth of a volt. The user could see changes as small as one one-thousandth of a volt, or 0.001. If a digital multimeter (DMM) has a resolution of 1 mV on the 3 V range, it is possible to see a change of 1 mV while reading 1 V.

Imagine a simple test of a 1.5 V household battery. One marked in 1/16-inch segments offers greater resolution than one marked in quarter-inch segments. Resolution is the smallest increment a tool can detect and display.įor a nonelectrical example, consider two rulers. Use of a DMM with higher accuracy allows a great number of applications. For example, an accuracy of ±(2%+2) means that a reading of 100.0 V on the multimeter can be from 97.8 V to 102.2 V. This may be fine for some applications, but unacceptable for sensitive electronic equipment.Īccuracy may also include a specified amount of digits (counts) added to the basic accuracy rating. A reading of 100.0 V on a DMM with an accuracy of ☒% can range from 98.0 V to 102.0 V. Some applications, such as calibration of automotive, medical aviation or specialized industrial equipment, may require higher accuracy. If a digital multimeter is only used to check if a receptacle is energized, a DMM with a ☓% measurement accuracy is appropriate. An example of this variation is a voltage measurement taken at a standard 115 V AC receptacle. For example, most AC power line voltages vary ±5% or more. The accuracy of a specific digital multimeter is more or less important depending on the application. Accuracy requires a comparison to an accepted industry standard. Precision: An instrument’s degree of repeatability-how reliably it can reproduce the same measurement over and over.Īccuracy refers to the largest allowable error that occurs under specific operating conditionsĪccuracy is expressed as a percentage and indicates how close the displayed measurement is to the actual (standard) value of the signal measured. Range: The upper and lower limits an instrument can measure a value or signal such as amps, volts and ohms. Resolution: The smallest increment an instrument can detect and display-hundredths, thousandths, millionths.

Accuracy: An instrument’s degree of veracity-how close its measurement comes to the actual or reference value of the signal being measured.

Range resolution calculator