What is kwh stand for?
It is easy to get kilowatt and kilowatt-hours confused as both are connected units of measurement. The important difference between kW and kWh is what they measure. A kW measures power i.e. the rate at which something uses electricity, whereas a kWh measures energy, the total amount of electricity used, or the capacity to use.
To truly understand kW vs. kWh, you also need to consider time. A kWh measures the energy an electrical device or load uses in kilowatts per hour. For example, if you charge your electric vehicle with a 22kW car charger for one hour, you will consume 22 kWh of energy. The equation is (kW x hours = kWh) to calculate kWh.
You can see kW vs. kWh or Power vs. Energy below. In these examples, we show, on the left-hand side, the power in kilowatts of a Level 2 (7.5 kW) and a Level 3 (60 kW) EV charging station. The kW number shows the rate at which these electrical devices consume power. On the right-hand side, you will see the energy consumed by these EV charging stations during a defined period of time, in this example 2 hours. Using the kWh equation (kW x hours = kWh), we can calculate the total energy consumed (7.5 kW x 2 hours = 15 kWh).
Let’s quickly summarize kW and kWh.
A kW or kilowatt is a unit of measurement for the rate of power an electrical device or load uses. The higher the kW of a device, the more electrical power is needed to operate it. A kilowatt is 1000 watts (W).
1000 W = 1 kW
A kWh or kilowatt-hour measures the energy usage of an electrical device or load. The higher the rate of power (kW) of an electrical device and the longer it is used (hours), the more electricity it consumes (kWh).
Let’s look at some examples of kW vs. kWh about both low and high-power electrical devices and see how they affect each other.
If you use a low-powered electrical device such as a 65-inch LED TV, which needs 100 watts (0.1 kW) of power, you can use it for ten hours before consuming 1 kWh of energy. On the other hand, if you are operating a 60 kW DC fast EV charger, you will consume 1 kWh of energy within one minute.
Understanding the difference between kW and kWh is essential for any business looking to monitor and manage its electricity usage. It is also crucial for any business looking to introduce EV charging, as utility companies typically charge for energy consumption in kWh and peak power demand in kW. Knowing when and at what rate electricity is being consumed can enable businesses to reduce their overall electric bills.
When it comes to Electric Vehicles (EVs), it is essential to know the difference between kilowatts and kilowatt-hours. An EV stores the electricity to propel itself in a battery; this battery is sized in kWh. Different EVs will have different-sized batteries; for instance, the Ford F-150 Lightning Pro has a battery capacity of 98 kWh, and the BMW i4 eDrive35 has a battery capacity of 70.2 kWh. While the battery of an electric vehicle is measured in kWh, the power needed to charge it is measured in kW. As a general rule, the higher kW (power) of an EV charger, the quicker its ability to charge the EV battery. However, when it comes to charging an electric vehicle, there are several variables to consider, including the EV charging level, EV charge acceptance rate, and size of the battery, all of which affect the time it takes to charge.
So, to summarize, in the EV world, kWh refers to the size/capacity of the battery, and kW refers to the power used to charge that battery. EV chargers are sized in kW, and the amount of time they are used will determine the energy consumed via the EV charger and delivered to the EV battery in kWh.
It’s easy to get kilowatt (kW) and kilowatt-hours (kWh) mixed up when talking about energy consumption. The main difference between kWh and kW is in what they measure. To put it simply, a kilowatt is a measure of power and a kilowatt-hour is a measure of energy; power is the rate at which something uses energy, and energy is the capacity to do work.
On your energy bill, the kWh measures the amount of energy that an appliance or device needs to run for one hour. Let’s break the definitions down a little further:
A kilowatt is simply a measure of how much power an electric appliance consumes—it’s 1,000 watts to be exact. You can quickly convert watts (W) to kilowatts (kW) by diving your wattage by 1,000:
1,000W 1,000 = 1 kW.
A kilowatt-hour measures the energy an appliance uses in kilowatts per hour. For example, if you clean your floors with a 1,000-watt vacuum cleaner for one hour, you consume 1 kWh of energy.
Your kilowatt-hour consumption factors in how many watts your appliances use and how often you use them. When you see kWh on your monthly energy bill, it’s a measurement of your electric appliances’ wattage and the amount of time you use them.
The difference between kWh and kW, and what you see on your bill, is that kW reflects the rate of electricity you use, and kWh indicates the amount of electricity you use. Let’s go over a few examples of kW vs kWh in the context of low- and high-power appliances to give you a better idea of how these two units affect each other:
The power you use on a daily basis can quickly add up to 1 kWh if you are frequently using high-wattage appliances in your home. Keep this in mind, as energy companies typically charge for power on a per-kWh basis.
Knowing the difference between kW and kWh can give you powerful insights to help monitor and manage your electricity consumption. To calculate the kWh of your appliance, estimate the amount of time you use it and write down the appliance’s wattage (generally found on the label). Remember that one kilowatt equals 1,000 watts, so don’t forget to divide your wattage by 1,000 to convert to kilowatts.
Let’s use a 1500W dishwasher you use for two hours per day as an example for calculating kW and kWh on a monthly basis:
Now that we know the monthly kWh for this device, let’s estimate the energy costs. Multiply the kWh by your electricity provider’s monthly electricity rates. For the sake of this example, we’ll say it’s $.07 per kWh:
90 kWh X $.07 per kWh = $6.30 per month
Make a list of appliances that you frequently use and do the same calculations. You can then start to balance your usage by examining which appliances require the most power (kW) and energy (kWh).
Utility companies measure your kWh with digital meters right outside of your home where the power line goes into the property. While traditional meters require a utility service to come to your home, newer digital meters have an electronic display that uses a high-frequency signal to send data to the utility companies.
Now that you have a better understanding of kW versus kWh, and the different uses of electricity, you can take a closer look at your bill and begin to analyze your energy consumption. For a more detailed understanding, consider investing in a home energy monitor. Many monitors available today are wireless and display your home’s energy consumption in an app. Depending on which monitor you choose, you may even be able to turn appliances on and off when you’re away from home using the app.
You can lower your electricity bill by being energy conscious and following some easy energy-saving practices. Replace incandescent lightbulbs with energy-saving LEDs and get in the habit of turning off the lights whenever you leave a room. Unplug or turn off appliances if you’ll be away from home for a few days, and resist the urge to leave your devices on standby when you don’t need them.
Look into buying smart power bars for parts of your home with several electronic devices (e.g. entertainment center, office). You can set a timer on a smart power bar so that it automatically turns off power to the devices overnight. Some smart power bars also cut power to all devices once you turn a specific device off. For example, you could program a smart power bar to cut power to your sound system and television as soon as you turn your gaming console off.
Once you know your usage per appliance, you can use this newfound knowledge to invest in energy-efficient home products. Most appliances and electronic devices have energy-efficient options. Look for the yellow ENERGY STAR® symbol on the appliance. ENERGY STAR® appliances are certified as energy-efficient and perform at the same or better level than similar products on the market.
So, when you’re ready to buy that new washer or dryer, be sure to check out the kW and kWh ratings and make some energy-saving adjustments, like washing with cold water and hang-drying your clothes.
Kilowatt hours, abbreviated as KWh, is a unit of energy representing one thousand watt hours. Kilowatt hours are often used as a measure of domestic energy consumption.
A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a non-SI unit of energy: one kilowatt of power for one hour. It is equivalent to 3.6 megajoules (MJ) in SI units. Kilowatt-hours are a common billing unit for electrical energy supplied by electric utilities. Metric prefixes are used for multiples and submultiples of the basic unit, the watt-hour.
The kilowatt-hour is a composite unit of energy equal to one kilowatt (kW) sustained for (multiplied by) one hour. Expressed in the standard unit of energy in the International System of Units (SI), the joule (symbol J), it is equal to 3,600 kilojoules or 3.6 MJ.[1][2]
A widely used representation of the kilowatt-hour is "kWh", derived from its component units, kilowatt and hour. It is commonly used in billing for delivered energy to consumers by electric utility companies, and in commercial, educational, and scientific publications, and in the media.[3][4] It is also the usual unit representation in electrical power engineering.[5] This common representation, however, does not comply with the style guide of the International System of Units (SI).[6]
Other representations of the unit may be encountered:
The hour is a unit of time listed among the non-SI units accepted by the International Bureau of Weights and Measures for use with the SI.[6] Its combination with the kilowatt, a standard SI unit, is therefore permitted within the standard.[dubious – discuss]
An electric heater consuming 1,000 watts (1 kilowatt), and operating for one hour uses one kilowatt-hour of energy. A television consuming 100 watts operating continuously for 10 hours uses one kilowatt-hour. A 40-watt electric appliance operating continuously for 25 hours uses one kilowatt-hour.
Electrical energy is typically sold to consumers in kilowatt-hours. The cost of running an electrical device is calculated by multiplying the device's power consumption in kilowatts by the operating time in hours, and by the price per kilowatt-hour. The unit price of electricity charged by utility companies may depend on the customer's consumption profile over time. Prices vary considerably by locality. In the United States prices in different states can vary by a factor of three.[11]
While smaller customer loads are usually billed only for energy, transmission services, and the rated capacity, larger consumers also pay for peak power consumption, the greatest power recorded in a fairly short time, such as 15 minutes. This compensates the power company for maintaining the infrastructure needed to provide peak power. These charges are billed as demand changes.[12] Industrial users may also have extra charges according to the power factor of their load.
Major energy production or consumption is often expressed as terawatt-hours (TWh) for a given period that is often a calendar year or financial year. A 365-day year equals 8,760 hours, so over a period of one year, power of one gigawatt equates to 8.76 terawatt-hours of energy. Conversely, one terawatt-hour is equal to a sustained power of about 114 megawatts for a period of one year.
In 2020, the average household in the United States consumed 893 kWh per month.[13]
In terms of human power, a healthy adult male manual laborer performs work equal to about half a kilowatt-hour over an eight-hour day.[14]
To convert a quantity measured in a unit in the left column to the units in the top row, multiply by the factor in the cell where the row and column intersect.
All the SI prefixes are commonly applied to the watt-hour: a kilowatt-hour is 1,000 Wh (kWh); a megawatt-hour is 1 million Wh (MWh); a milliwatt-hour is 1/1,000 Wh (mWh) and so on. The kilowatt-hour is commonly used by electrical energy providers for purposes of billing, since the monthly energy consumption of a typical residential customer ranges from a few hundred to a few thousand kilowatt-hours. Megawatt-hours (MWh), gigawatt-hours (GWh), and terawatt-hours (TWh) are often used for metering larger amounts of electrical energy to industrial customers and in power generation. The terawatt-hour and petawatt-hour (PWh) units are large enough to conveniently express the annual electricity generation for whole countries and the world energy consumption.
Sometimes[when?] there is confusion[according to whom?] between the kilowatt and the kilowatt-hour (not kilowatt per hour, as sometimes[when?] misused[by whom?]). Work is the amount of energy transferred to a system; power is the rate of delivery of energy. Energy is measured in joules, or watt-seconds. Power is measured in watts, or joules per second.
For example, a battery stores energy. When the battery delivers its energy, it does so at a certain power, that is, the rate of delivery of the energy. The higher the power, the quicker the battery's stored energy is delivered. A higher power output will cause the battery's stored energy to be depleted in a shorter time period.
Electric energy production and consumption are sometimes reported on a yearly basis, in units such as megawatt-hours per year (MWh/yr) gigawatt-hours/year (GWh/yr) or terawatt-hours per year (TWh/yr). These units have dimensions of energy divided by time and thus are units of power. They can be converted to SI power units by dividing by the number of hours in a year, about 8766 h/yr.
Thus, 1 GWh/yr = 1 GWh/8766 h ≈ 114.08 kW.
Many compound units for various kinds of rates explicitly mention units of time to indicate a change over time. For example: miles per hour, kilometres per hour, dollars per hour. Power units, such as kW, already measure the rate of energy per unit time (kW=kJ/s). Kilowatt-hours are a product of power and time, not a rate of change of power with time.
Watts per hour (W/h) is a unit of a change of power per hour, i.e. an acceleration in the delivery of energy. It is used to measure the daily variation of demand (e.g. the slope of the duck curve), or ramp-up behavior of power plants. For example, a power plant that reaches a power output of 1 MW from 0 MW in 15 minutes has a ramp-up rate of 4 MW/h.
Other uses of terms such as watts per hour are likely to be errors.[15][16]
Several other units related to kilowatt-hour are commonly used to indicate power or energy capacity or use in specific application areas.
Average annual energy production or consumption can be expressed in kilowatt-hours per year. This is used with loads or output that vary during the year but whose annual totals are similar from one year to the next. For example, it is useful to compare the energy efficiency of household appliances whose power consumption varies with time or the season of the year. Another use is to measure the energy produced by a distributed power source. One kilowatt-hour per year equals about 114.08 milliwatts applied constantly during one year.
The energy content of a battery is usually expressed indirectly by its capacity in ampere-hours; to convert ampere-hour (Ah) to watt-hours (Wh), the ampere-hour value must be multiplied by the voltage of the power source. This value is approximate, since the battery voltage is not constant during its discharge, and because higher discharge rates reduce the total amount of energy that the battery can provide. In the case of devices that output a different voltage than the battery, it is the battery voltage (typically 3.7 V for Li-ion) that must be used to calculate rather than the device output (for example, usually 5.0 V for USB portable chargers). This results in a 500 mA USB device running for about 3.7 hours on a 2,500 mAh battery, not five hours.
The Board of Trade unit (B.T.U.)[17] is an obsolete UK synonym for kilowatt-hour. The term derives from the name of the Board of Trade which regulated the electricity industry until 1942 when the Ministry of Power took over.[18] This should not be confused with a British Thermal Unit (BTU) which is 1055 J.
In India, the kilowatt-hour is often simply called a Unit of energy. A million units, designated MU, is a gigawatt-hour and a BU (billion units) is a terawatt-hour.[19][20]
While both are interrelated units of measurement, the important distinction between kWh and kW is that a kWh reflects the total amount of electricity used, whereas a kW reflects the rate of electricity usage.
Technically, the difference is that a kWh is a measurement of energy, while a kW is a measurement of power; however, the terms power and energy are often mistakenly used interchangeably. Energy refers to the ability to do work - power refers to the rate of energy production or consumption. To really understand kWh and kW, you also need to consider time.
In order to quantify the actual amount of electricity consumed, there needs to be a period of time in which that rate occurs. 1 kWh equals one hour of electricity usage at a rate of 1 kW, and thus the 2 kW appliance would consume 2 kWh in one hour. The equation is simply (kW x Time = kWh).
Why does the difference between a kWh and kW matter for businesses? While it seems like a scientific differentiation, paying attention to these measurements can lower your energy bills.
Most utilities bill customers for total kWh energy consumption and peak kW power consumption. Knowing when, and at what rate energy is consumed, allows customers to manage and reduce electricity costs.
Suppose that the electricity rate for commercial customers is 12.22 cents/kWh and $15.45/kW during peak hours. A 2 kW appliance that ran for 100 hours in a month would equal 200 kWh and therefore cost $24.44 in kWh consumption charges and $30.90 in kW demand charges. That’s why it can be beneficial to use devices that consume electricity at a lower rate. If that appliance ran at a more efficient 1-kW rate, the total cost would be cut in half, assuming it ran for the same amount of time.
However, a lower kW device may not always function the same as a higher kW one. It would have to run for longer periods of time during high-cost periods in order to generate the same amount of energy.
LED light bulbs can run at a lower wattage for the same amount of time as a higher wattage device like an incandescent bulb because an LED bulb does not let as much energy escape (as heat) and requires less energy to have the same lighting capabilities.
A kilowatt hour (kWh) is a measure of how much energy you’re using per hour, whilst a kW is a measure of power. kW stands for kilowatt, a universal standard for measuring electricity. So, one kilowatt equals 1,000 watts. Your electricity provider charges by how much electricity you use per kilowatt hour (kWh). The kWh is a unit of energy, the number of kilowatts you use over time, on different things.
Energy is a measure of how much fuel is contained within something or used by something over a specific time period. Think of it like a Mars bar- the kWh is the like calories (or energy) within the bar, the kW is how you use those calories.You might go for a fast, high-intensity run and burn off the energy in a matter of hours, or you might loaf on the sofa binging on Netflix, therefore stretching that energy out a bit. So, the electricity cost per kWh price you pay depends on how long you keep everything on. That’s why leaving your TV on standby or your charger plugged in still uses power and will add to the kWh cost on your energy bill (and wastes energy).
Say you have ten 100-watt light bulbs, that would equal 1kW of energy usage (10 x bulbs x 100W = 1,000W= 1 kW). To work out the kWh cost, you’d multiply that by the amount of time you need them on and the electricity cost per kWh:
1kW x 10 hours x £0.34 electricity cost per kWh = £3.40 a day
Boom! It’s that simple! Take another look at your energy bill and you’ll see it start to make more sense.
You can apply this rule to your gas too (it will have a different unit cost than your electricity though).
According to the Energy Saving Trust, the national average price (as of October 2022) per pence/kWh of electricity is £0.34. This is for illustration purposes only. Your exact unit cost depends on your supplier, meter type, where you live, what tariff you're on and how you pay.
We supply the kW power to meet the “demand” of our customers and demand determines the price. The price varies, depending on your supplier, tariff, meter type, and region type. According to the Energy Saving Trust, the national average price for kWh in pence is £0.34. There are two main factors you can focus on when choosing your electricity and gas tariff:
When comparing energy deals, check these carefully. Whilst a tariff might have a low kWh unit rate, the price of the standing charge may be high, so check before you sign up.
How much did that morning cuppa cost you? Is it important? Yes! Here’s why it’s worth knowing what electricity price you pay per kWh and how to easily convert your electricity cost per kWh into pounds and pence.
Now you know how much 1 kWh of electricity costs and how to convert kWh into pounds and pence. You can quickly check your home to work out your average kWh per day and find out where you can make changes to save on your energy bill.
Here are our three easy steps to help save on your energy bill and reduce your carbon footprint:
Everything with a switch costs you money and has an impact on your carbon footprint size. Say you have a brand-new large-screen TV with a 500 W power rating (kW rating of 0.5) – and you want to know how much it costs to run. Multiply 0.5 by the time you spend watching it – say 4 hours a day. Your 0.5 kW TV uses 2 kWh per day.Now, look at your energy bill. If your electricity price per kWh is £0.34, your TV will cost £0.68 per day to run (0.5kW x 4 hours x £0.34). This may not sound like a lot but it adds up to £248.2 a year - on top of everything else you’re using.Here are a few more examples of standard home appliances and how much they cost to run:
These examples are just a fraction of what you use in your home but highlight how you can add things up to work out your average daily kWh use.
If you've got central gas heating you can work out how much you're spending on heating your home, based on the national average kWh gas price of 10.3p.
Remember, if you hate maths you can always get a smart meter, which shows you what you're spending and where in real-time via a handy in-home display.
All good habits start right here, right now. Once you know your kW from your kWh and the amount of time you use things, you can build a profile of the kind of energy user you are and where you can reign things in. Are you a heavyweight or a featherweight energy user? Where are the hotspots in your home? Do you leave laptops plugged in? TV on standby?
You’ve heard of the 5/2 diet - maybe allow yourself that extra spin on the dryer at the weekend, but dry outdoors or overnight the rest of the week. Try to take a break at tea-time so you don’t have to re-boil the kettle ten times. You can also seek out energy-efficient appliances like smart lightbulbs or washing machines.
Next time you choose a tariff, you'll feel in greater control of your choices and finances. Feels good, doesn’t it? If you're on an EDF tariff, you find the exact pricing details on your tariff information label. You can also view our tariffs and compare prices.
By understanding how much you spend on energy and on what appliances, you will:
Hopefully, you now know your kW from your kWh. And you can make positive changes to the way you use and save energy. This in turn will have a positive impact on your wallet and the planet!
To find out more about saving energy and cutting your carbon take a look at our energy efficiency tips.
