The Difference Between Watts vs. Volts

Understanding the difference between watts and volts is key to grasping basic electrical concepts. While they are related, watts and volts measure two different aspects of electricity. Knowing how to distinguish between the two will allow you to better understand electrical power and make informed decisions when purchasing and operating electrical devices.

What is a Watt?

A watt is a unit of power that measures the rate of energy conversion or transfer. Specifically, a watt quantifies how much power is used by an electrical device or system.

The wattage of a device shows how much power it consumes to function properly. For example, a 100-watt light bulb requires 100 watts of electrical power to produce illumination.

Some key facts about watts:

  • Watts measure power, or the rate at which energy is converted.
  • Higher wattage equates to more power consumption.
  • Wattage indicates how much electricity a device uses.
  • The wattage rating is commonly marked on electrical devices and appliances.
  • Watts are determined by multiplying volts and amps (Watts = Volts x Amps).

Understanding wattage gives you an idea of how much power a device will draw from an electrical system. Comparing watts between similar devices also shows which is more energy efficient. Knowing the wattage requirements will ensure your electrical system can handle the load.

What is a Volt?

Unlike watts, volts are a unit of electrical potential difference. Voltage measures the “push” or electrical pressure that causes current to flow through a circuit.

For example, a typical household electrical outlet will supply 120 volts. This voltage produces an electric field that exerts force on electrons in a circuit, causing them to move.

Here are some key details about volts:

  • Volts measure electric potential difference or “voltage.”
  • Voltage pushes electric current to flow in a circuit.
  • Higher voltage allows more current to flow.
  • Common volt ratings are 120V (typical North American household outlets) and 230V (typical European household outlets).
  • Devices are designed to operate at specific voltages.

Understanding voltage allows you to see how much electrical force is supplied to a device. Higher voltages enable larger amounts of current to flow in a circuit. However, each device is also designed to operate within specific voltage tolerances for safety and efficiency.

The Relationship Between Watts and Volts

Watts and volts are directly related, but they measure complementary electrical properties. The power consumption in watts is determined by multiplying the volts and amps:

Watts = Volts x Amps

Volts supply the electric potential difference or “pressure.” Amps measure the amount of electric current flow. Multiplying volts and amps together gives you the wattage, which reflects how much power the device consumes.

Think of it like a water pipe. Voltage is like the water pressure – it “pushes” the flow of electricity. Amperage is the rate of current flow. Watts are like the total water volume moved over time. Volts x Amps gives you the total power used.

While interrelated, volts and watts still serve different primary purposes:

  • Volts: Enable current flow in a circuit. Higher volts allow more current.
  • Watts: Measure power consumption. More watts means more energy used.

Real World Examples of Watts and Volts

Let’s look at some real-world examples to understand the practical difference between watts and volts:

Electrical Outlets

A standard electrical outlet in North America supplies 120 volts. This voltage exerts the electric force that allows current to flow to an appliance plugged into the outlet.

The wattage depends on the appliance. For example, a 1200 watt hair dryer will draw 12 amps (1200W / 120V = 12A). A 60 watt light bulb draws just 0.5 amps (60W / 120V = 0.5A).

So the volts supply consistent electric potential to the outlet, while the wattage varies based on the appliance.

LED Light Bulbs

Comparing light bulb wattages shows the power consumption difference. An incandescent bulb uses 60 watts. An LED bulb may produce the same brightness with just 12-15 watts.

But both bulbs operate on the standard 120 volts supplied by household outlets. Lower wattage LED bulbs use less electricity while outputting similar light levels.

Electric Vehicles

Electric vehicles use rechargeable batteries instead of gasoline engines. Their efficiency is measured in watt-hours per kilometer (Wh/km). A lower Wh/km rating equates to less power used per kilometer driven.

Onboard chargers refill the batteries using household 120V or 240V outlets. The voltage remains constant, but the EV wattage consumption varies widely depending on driving distance and battery capacity.

Wattage Ratings for Common Electrical Devices

To better understand practical wattages, here are some examples for household electrical devices:

  • Light bulbs: 40W, 60W, 75W, 100W
  • Laptop charger: 45W, 60W, 90W
  • Desktop computer: 500W Power Supply Unit
  • LCD TV: 120W, 200W, 300W
  • Electric oven: 1,800W – 5,000W
  • Gas furnace blower motor: 750W
  • Window AC unit: 500W – 1,500W
  • Space heater: 750W, 1,500W
  • Clothes dryer: 1,800W – 5,000W
  • Vacuum cleaner: 500W – 1,500W
  • Hair dryer: 1,200W – 1,875W

Higher wattages indicate more power consumed. But almost all household devices in North America run on between 110V to 120V supplied by standard outlets.

Choosing Electrical Devices Based on Watts and Volts

The main considerations when choosing electrical devices are:

  • Intended voltage – Make sure the device is designed for the voltage of your electrical system.
  • Wattage rating – The power consumption impacts energy efficiency and electricity costs.
  • Maximum load – The total wattage used by all devices should not exceed the system capacity.

Here are some tips specific to watts and volts when selecting electrical items:

  • For volts, choose devices that match your exact electrical system voltage and frequency. Do not exceed the voltage ratings.
  • For watts, calculate the total load and maximum demand based on appliance wattages. Higher wattages increase costs.
  • Favor more energy efficient devices with lower wattage for the same output. This reduces electrical load.
  • For outlets, use the rated current and voltage to avoid overloading circuits. This prevents tripping breakers.
  • Use surge protectors if necessary to prevent voltage spikes from damaging electronics.

Considering watts and volts ensures your devices work properly without overtaxing your electrical system. Understanding these basic units also helps guide upgrades like installing more circuits or higher capacity service panels.

Frequently Asked Questions About Watts and Volts

Here are some common questions that arise when comparing watts vs. volts:

How are watts different from volts?

Volts measure electrical pressure, while watts measure power consumption. Voltage pushes current to flow. Wattage reflects how much power a device uses. Think of volts like the “pressure” and watts as the “flow.”

Can I use a device with a different voltage?

Devices are designed for specific voltages. Using an incompatible voltage can damage electronics or be unsafe. Always check the voltage rating and use devices with voltages matching your electrical system.

Why does higher wattage use more electricity?

Since watts measure power consumption, a higher watt rating equates to more electricity used. Comparing watts between similar appliances shows which uses more energy.

How do I calculate the wattage of a device?

Use the formula Watts = Volts x Amps to determine wattage. For example, a 10 amp appliance on a 120 volt circuit uses 1200 watts (120V x 10A = 1200W).

Why are some devices more energy efficient?

Advanced technology allows more efficient energy conversion. LED lights use less watts than incandescent bulbs to produce the same brightness. Efficient motors, insulation, and designs also reduce energy waste.

Can I plug in multiple high wattage devices?

You need to ensure the total wattage load does not exceed your electric service capacity. High demand may trip breakers. Large loads may require upgraded electrical service.

How do electric vehicles use watts and volts?

EVs use onboard batteries and electric motors instead of engines. They recharge using household 120V or 240V outlets. The voltage stays constant while the wattage consumption varies.


In summary, watts and volts provide complementary pieces of electrical data:

  • Watts measure the power consumption and rate of energy transfer in a circuit. The wattage reflects how much electricity a device uses.
  • Volts quantify the electric potential difference or “pressure.” Voltage enables current to flow in a circuit.
  • While interconnected, watts show the power used and volts show the electrical force supplied.
  • When selecting electrical devices, consider the wattage, voltage rating, and total load capacity.
  • Understanding both watts and volts provides a better picture of electrical efficiency and requirements.

Knowing the distinction between watts vs. volts empowers you to make informed decisions when operating, choosing, and upgrading electrical devices and systems. Consider both the wattage power consumption and voltage requirements to maximize efficiency while safely powering your home and equipment.