Have you ever tried to read your power bill and not really understood what it all means?
Or perhaps you’re trying to set up an off-grid power supply like solar panels and power inverters.
It’s easy to get confused when it comes to electrical and energy terms like watts, kilowatts, watt-hours, energy, volts, amps, and more!
They’re all related but slightly different and so-called ‘simple explanations’ don’t always actually answer your questions.
You’ve probably already read that a Watt is a measurement of power.
But what does that actually mean? Let’s find out.
What is a Watt?
You can imagine watts like miles per hour.
It is quite simply the rate or speed at which energy flows. For electricity, it’s the measurement assigned to how fast electrons travel down wires into appliances.
So you measure how fast a car is going in miles per hour e.g. 40 miles an hour.
You would talk about watts in the same manner e.g. A light bulb uses 60 watts.
The symbol for a watt is ‘W’.
The next thing to understand is watt-hours. Watt-hours are a measurement of energy which is essentially how much electricity your device consumes in an hour. So 60 watt-hour is the amount of energy that a light bulb uses in an hour.
The symbol for watt-hour is ‘Wh’.
If you struggling to understand the difference between watts and watt-hours then picture it like this –
- A watt is a snapshot of power at a single moment in time.
- A watt-hour is the total amount of energy consumed.
- If a watt is a bit like the speed of a car then a watt-hour is like the distance traveled in an hour.
What is a Kilowatt-hour (kWh)?
When you look at a power bill you’ll see another term which is Kilowatt-hour or ‘kWh’.
1 Kilowatt is 1000 watts.
It is just a more convenient way of referring to the large amounts of power you use at home. The word Kilo is used in the metric system to refer to the word ‘thousand’ which is derived from ancient Greek. It’s just like Kilometer means 1000 meters.
So when trying to work out the difference between watts and kilowatts it’s very simple. You just multiply or divide by 1000.
To turn watts into kilowatts just divide by 1000. For example:
50 watts divided by 1000 = 0.05 kilowatts
To turn kilowatts into watts just multiply by 1000:
0.05 kilowatts x 1000 = 50 watts
Once again a kilowatt is a snapshot measurement of the speed of electricity while a kilowatt-hour is the total amount of energy consumed in one hour.
What is Power?
Power is the rate at which energy flows. It’s the speed of the electricity in your cables. The word watt (W) or kilowatt (kW) is used to refer to this.
What is Energy?
Energy is the capacity to do the work. Basically, it is how much electricity is consumed to complete an action. Watt-hour (Wh) or kilowatt-hour (kWh) are used to refer to this.
Why is it Called A Watt?
The Watt is named after the Scottish engineer and inventor James Watt. You’ve probably heard his name mentioned before and for good reason. He is credited with the invention of the modern steam engine which was key to the industrial revolution. When the decision was made to come up with a name for ‘a unit of power’ in 1882 William Siemens came up with the idea of Watt in a speech to the British Association of Advancement of Science.
What is Equivalent to a Kilowatt?
1 kilowatt is the equivalent of 1.34 horsepower. Or 1 horsepower is the same as 0.745 kW / 745 W.
To put that into perspective the Ferrari Enzo has 650 horsepower that’s about 485kWh!
How Many Watts Are Your Appliances?
One big question people ask is how many watts their home appliances and gadgets use. Know these details can help you understand where you can reduce your energy bills. Plus if you have an off-grid electricity supply like a solar panel you can work out what appliances you can run on your inverter. Here’s a list of common appliances and an average watt rating.
| Device | Average Watts |
| Laptop | 20 – 80 |
| Tablet | 10 – 20 |
| Smartphone | 10 |
| Coffee maker | 700 – 1500 |
| Microwave | 700 – 1200 |
| Space heater | 1500 – 2000 |
| Refrigerator | 60 – 250 |
| Mini fridge | 40 – 100 |
| Fan | 50 – 80 |
| 32” LED TV | 50 – 70 |
| Games Console | 80 – 150 |
| Power tools | 1000 – 2000 |
Ways to Work Out the Wattage of a Device
There are a number of easy ways to find the wattage of any device. Once you know the wattage you’ll be able to work out how much energy you’re likely to use and what you can run from an electricity source like solar panels or power inverters.
- Multiply volts by amps to get watts. For example, 12 volts x 5 amps = 60 watts
- Use a wattmeter. A wattmeter is a very handy piece of kit you can plug any appliance into to get the wattage. Highly recommended!
- You’ll usually find the watt rating of electronics on the product technical information, especially with power-related things like inverters and solar panels.
How are Energy Costs Calculated?
Once you understand the basics of watts and kilowatts you can easily read your energy bill and calculate costs. On an energy bill, the amount of energy you use is marked as kilowatt-hours.
All you need to do is multiply kilowatt-hours (kWh) by energy unit price to get your total cost.
For example, if your energy total usage is 100kWh and you pay $0.13 per kWh, you simply multiply 100kWh x 0.13 = $13 (a cheap bill but you get the basic maths.)
Simple Guide to Watts, Amps, and Volts
Watts: The speed energy travels. (like the speed of water in a hose)
Amps: The amount of current (like the diameter of a hose)
Volts: The pressure of electricity (like water pressure in a hose)
FAQ About Watts
Which is bigger kilowatts or Watts?
Kilowatts are 1000 times bigger than watts. For example, 1 kilowatt is 1000 watts.
The same is true of watt-hour and kilowatt-hour. If you consume 1 kilowatt an hour (kWh) that is the equivalent of 1000 watts an hour (Wh).
What is a Megawatt?
A Megawatt is one million Watts. The symbol for this is MW.
What is Gigawatt?
A Gigawatt is one billion Watts. the symbol for this is GW.
Does higher Watts mean more power?
Yes, a watt is a measurement of power so the higher the watts the higher the power. For example, it means that an appliance that draws 1000 watts is more powerful than an appliance drawing 100 watts. The more watts the quicker a machine can consume energy.
Watts vs Amps
Watts is a unit of power (how fast energy flows) and amps is a unit of current flow specifically for electricity. Amps are the strength of an electrical current. Amp is like the diameter of a hose, the wider it is the more water can flow through it. This is similar to amps and electricity flow through a cable.
To work out watts you multiply volts by amps.
To work out amps you divide watts by volts.
Watts vs Volts
A watt is a unit of power, or how ‘fast’ energy is flowing. Volts is the electrical potential difference between two places. Think of Volts as pressure in a wire, a bit like water in a hose. A battery with higher is able to ‘push out’ the electricity faster to enable a higher wattage.
To work out voltage you multiply watts by amps.
To work out watts you multiple volts by amps.
How many volts are in a watt?
You can’t compare the number of volts in a watt as they are two different measurements. Watts are a measurement of power ‘speed’ of energy while volts are a measure of potential difference similar to the pressure of water in a hose.
Does more watts mean brighter?
No, watts does not directly mean a brighter light. Light brightness is measured in lumens, although a higher lumen light usually requires more watts. The invention of LED lights means this is not a strict rule. A lower watt LED light is often brighter than a higher watt traditional candescent light bulb.
Does more watts mean more sound?
Generally speaking, a speaker or amplifier with more watts will be louder. That being said, there are a number of factors that determine the overall volume of a speaker. You should also check the decibels of dB. The higher the dB means more sound.
Is it ok to use a higher watt light bulb than a lamp?
If you use a lightbulb with a higher wattage rating than the lamp then it can quickly lead to overheating. This can be very dangerous as it can melt the socket and wires in the lamp which could lead to a fire. You will risk damaging your lamp and lead to a very big safety risk. For example, you should not use a 60 watt bulb in a 40 watt light as the power will be too much for the lamp to handle.
Do we pay for amps or watts?
In actual fact, you pay your energy bill based on kilowatt-hours (kWh). Watt-hours and kilowatt-hours tell you how much energy has been used. To work out what your energy bill is you multiply the total kilowatt-hour by energy unit price. On average, Americans pay around $0.13 per kWh.
What appliances use the most power?
In the home, the appliances that use the most power are often things that require a heating element or motor. The highest energy consumers are usually heaters and coolers, water heats, washers, and dryers. You also find that other devices use a lot of power but you might only use them for short periods of time. Things like power tools, coffee machines, microwaves, blenders, and hairdryers will draw a lot of watts when in use.
