Potential difference, current and resistance are three primary parameters that are associated with any electronic or electrical circuit. All three parameters can be quantitatively measured using suitable instruments. An ammeter is an electrical instrument used to measure flow of current through an electrical or electronic circuit. Similarly, potential difference between two points in an electric circuit can be measured by voltmeter, while resistance can be calculated mathematically from known voltage and current or it can be measured directly with the help of either diode or multimeter.

In fact, a multimeter can directly measure all of the above three properties. Therefore, a multimeter is one multi-purpose electrical instrument that can directly measure potential difference, current as well as resistance of an electric circuit. Some multimeters can also measure few other parameters link frequency, capacitance, inductance, humidity, etc. Similarities and differences between ammeter and multimeter are discussed in the following sections.

Similarities between ammeter and multimeter

• Both ammeter and multimeter are electrical instruments and thus can work only in presence of electricity in a circuit.
• Both the instruments can measure electrical current flowing through an electric circuit in ampere or milli-ampere unit.
• Both of them has analog and digital version.

Differences between ammeter and multimeter

Ammeter	Multimeter
Ammeter is used to measure electric current flowing through an electric circuit.	Multimeter is a multi-purpose instrument that can directly measure various parameters like potential difference, current, resistance, frequency, capacitance, etc.
To measure resistance of a circuit, a voltmeter is also required along with ammeter.	Multimeter can directly measure resistance of a circuit. So no need to use a separate voltmeter for this.
It is generally not used to test diodes or transistors.	Multimeter can be used to test diodes and transistors.
Ammeter cannot substitute multimeter.	A multimeter can substitute an ammeter.
Ammeters are comparatively cheaper.	Multimeters are costlier as they consist of multiple parts for measuring various parameters.
Area of application of ammeter is narrow.	Multimeters have a wide area of applications for its capability to perform multifarious functions.