Watts vs. Volts: What’s the Difference?

Working with your electrical system, whether you’re fixing wiring or changing a light bulb, requires understanding watts and volts. The two terms are not interchangeable as many people believe. Voltage is measured in volts and rate of power flow is measured in watts. To help you understand the watts vs. volts discussion, we have created this infographic.

Watts vs. Volts

What Is a Volt?

A volt (V) is a measure of voltage. Circuits require a certain number of volts to supply power to lights, devices, and appliances; one volt equals 1000 watts or .001 kilowatts (kW) per hour.

It is the potential difference between two points of a conducting wire.
The wire must have a constant current of 1 ampere (Amp) when 1 watt of power dissipates between the same two points.
Voltage is the speed of electrons as they pass a certain location in a circuit. It can be compared to water pressure in pipes.

Also called electromotive force, voltage measures the pressure needed for a power source to push charged electrons through a conducting material.

Power ratings are often simplified using volt-amperes (VA) to calculate current draw. Volt-amperes are calculated by multiplying the voltage by the current to determine the apparent power in a DC circuit, which is the same as the circuit’s real power.

If you know the voltage of a circuit or device, you can determine the amount of current that it draws. This is important if, for example, you need to know how much power will be drawn through a 120 V circuit by plugging in an appliance.

What Is a Watt?

A watt is a unit of power that helps determine how much power is needed to perform work or generate heat. Wattage, which is akin to horsepower in an engine, is the rate of energy used by a device.

Watts are calculated by multiplying the voltage by the current in a DC circuit.
Power in watts is the rate at which energy is either consumed or generated.
One watt equals one joule (a measure of energy) per second (1 W + 1 J/s).

Utility companies charge rates based on watts, or power consumed over a given time. Typically, electricity usage is expressed in kilowatt-hours. If you leave a light bulb on for 10 hours, it consumes 1 kW hour of energy. Wattage ratings can help:

Know how much to pay a utility company to use a certain device.
Eliminate heat that a device consuming the watts generates.

Calculating real power for AC circuits is more difficult because you need to know the instantaneous voltage with time and the instantaneous current with time (but instantaneous power changes over time, so therefore you need to determine an average value).

*While this can be visualized on a waveform, calculating it is challenging.

Related Electrical Terms

When you consider the difference between watts vs. volts, it helps to understand other terms, such as:

Current: The measure of flow through electrical circuits, which helps to know how powerful an electrical source is.
Resistance: Measured in ohms, it’s a measure of how easily electrons move through a material.
Amperage: Amount of current than can run through a wire; a low amperage can cause a wire to overheat or breaker to trip.

Watts and volts do not act independently. Without voltage, there can be no watts in a wire or circuit. So therefore, each acts on one another and are important for knowing the capacity of your electrical system and ensuring electrical safety.

Contact Express Electrical Services

The understanding of watts vs. volts is important. If you require electrical repair, maintenance, or need help with electrical installation, our licensed electricians can help address the needs of your Southern California home. We offer same-day service and are available 24/7 to help in emergencies. Also, we offer access to financing to make installation more affordable. Call 323-727-7799 to request a visit or for answers to additional questions you may have.