Difference Between Watts and Volts


Main Difference

The main difference between Watts and Volts is that Watts are the SI unit of power, whereas Volts are the SI unit of potential difference and electromotive force.

Watts vs. Volts

The units of power are called watts, whereas the units of potential difference and emf are called volts. Multiplication of volts with the current gives the unit of power, watt. On the contrary, dividing potential energy by charge gives the unit of potential difference, volt.

Watt is denoted by symbol W, whereas volt is denoted by symbol V. Measurement of reading of watt is difficult. On the other hand, the measurement of reading of volt is comparatively easier. Watt can measure the exact power that exists naturally. On the flip side, volt can measure only a small amount of voltage from the power supply.


The measuring apparatus for calculating watts is a power meter. On the contrary, the measuring apparatus for calculating volts is a voltmeter. The base units for watts are given as kilogram meter square per ampere per cube second. On the flip side, the base units for volts are given as kilogram meter square per cube second.

If we want to know the watt reading, we must know the values of both current and voltage. On the flip side, to know the volt reading, we must know the values of current passing and resistance that opposes the flow of the current.

Most electrical devices do not show the value of watts, whereas the potential difference readings are apparent on most electrical devices in the form of volts. Watt reading can be determined indirectly by Ohm’s law. Conversely, volt reading can be taken by Ohm’s law directly.


Comparison Chart

The unit of measurement of power is called watt.The unit of measurement of potential difference or electromotive force is called volt.
SI Unit
PowerPotential difference
Kg M^2 A^-1 S^-3Kg M^2 S^-3
Taken with difficultyTaken easily
Measures accurate powerMeasures small voltage from the power supply
Measuring Apparatus
Power meterVoltmeter
Potential energy / chargeVolts x current

What are Watts?

The SI unit of power, which is equivalent to one joule per second, is called watt. The rate of consumption of energy in an electric circuit where the potential difference is one volt and current is one ampere is also known as the definition of a watt.


The name of the unit watt is derived from the name of the inventor of a steam engine, James Watt. Watt is also defined as the rate of the current flow with a potential difference in volts. If a current of one ampere passes through the electrical circuit of potential difference one volt, then the power is given as one watt.

If one joule of energy is consumed in one second, the power is one watt. After calculating the potential difference and current through the electrical circuit, we can say that one watt carries a hundred volts. It is concluded employing the power equation as watt = ampere x volt.

If power is unknown, but voltage and current are known, power can be calculated as P = VI. Power reading is taken with much difficulty as compared to a potential difference. A power meter is connected in series to measure the power of the system. Horsepower is a bigger unit of power. It contains 746 watts. One kilowatt contains 1000 watts.


  • A central heating furnace uses 340 watts.
  • A portable electric fan heater uses 2000 to 3000 watts.
  • A central air conditioner uses 1000 to 4000 watts.

What are Volts?

The SI unit of electromotive force or potential difference is called volt. The difference of potential carrying one ampere of current against the resistance of one ohm is one volt. It can also be described as the energy usage of one joule when the electric charge of one coulomb passes.

The force, which makes the electric charges move, is called voltage. The assertive unit that enables the charges to travel in a wire or some other electrical conductor is called voltage. It can also be termed as an electromotive force. The electric potential difference, which is the variance in electric potentials between two dissimilar points in the same electrical circuit, is called voltage.

The unit “volt” is designated after an Italian physicist Alessandro Volta. Current is the effect, where voltage being the cause. The potential difference between two points in an electrical circuit, results in the flow of current from a positive terminal of the battery to the negative terminal of the battery.

The magnitude of the force that conducts the electrons through a circuit is called volt. Volts are measured by connecting a voltmeter in parallel in a circuit. A voltmeter cannot be connected in series as a voltage is divided among all the resistors in series.

A power supply of 12 volts delivers a current of 1 ampere. One kilovolt contains 1000 volt, whereas one millivolt contains 0.001 volts.


Most applications consume a voltage of 120 volts. Some appliances like cloth dryers and electric cooktops use a voltage of 240 volts.

Key Differences

  1. Watt is referred to as the energy usage of one joule in one second. On the other hand, the volt is referred to as energy usage by a charge of one coulomb.
  2. One watt is given as the power consumed when the current of one ampere flows with the potential difference of one volt across the two ends of a current-carrying conductor. On the flip side, one volt is given as the potential difference that would carry a current of one ampere against the resistance of one ohm.
  3. The name of the unit watt is named on the name of an inventor, James Watt. Conversely, the name of the unit volt is derived from the name of an Italian physicist Alessandro Volta.
  4. Watts resembles to rate. On the flip side, volts resemble to pressure.
  5. Watts is an amalgamation of volts and amperes. On the contrary, volts are calculated by the division of energy consumed per coulomb of charge.
  6. Watt has no relation with current and resistance in Ohm’s law. Conversely, the volt is related to current and resistance in Ohm’s law.
  7. Current does not increase by increasing volts. On the flip side, current increases by increasing the volts.
  8. The reading of power in terms of watts is taken with difficulty. In contrast, the reading of potential difference or an electromotive force in terms of voltage can be taken easily as compared to watts.
  9. The measuring device used to measure power in terms of watts is called power meter. On the flip side, the measuring device used to measure the potential difference in terms of volts is called a voltmeter.
  10. Power meter measures the exact power in the electrical circuit. On the contrary, the voltmeter measures a small amount of voltage from the power supply in the electrical circuit.


The energy utilized by the devices in one second is called watt, whereas the energy utilized by the electrons from one end to another is called volt.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss