Watts to Kilowatt Hours (W to kWh) Conversion Calculator


Energy in Kilowatt-Hours:

kWh * hrs / 1,000 =

0.00 kWh

Conversion formula: kWh = (W * hrs) / 1,000

What is Watts?

Watts is the unit for power. When applied to electrical systems, it is rate at which an electric circuit uses energy. In other words, it is the amount of energy an electrical system consumes or produces per unit time.

Watts is typically represented with W.

What is Kilowatt Hours?

Kilowatt-hours is a unit typically used for electrical energy. It is the amount of power (in kilowatts) used or produced over a given number of hours. In other words, one kilowatt-hours is equivalent to a power consumption or production of one kilowatt over one hour.

Kilowatt-hours is typically represented with kWh.

Why Convert Watts to Kilowatt-Hours?

We primarily convert W to kWh to figure out the energy usage of our devices.

Typically, electrical devices come with watts rating, which gives us an idea of their maximum power consumption. But when we want to know the energy consumption of the devices, we must convert the watts rating to kilowatt-hour.

Calculating kilowatt-hours for our devices gives us an idea of how much electricity we are using. With this, we can estimate electricity cost.

Converting watts to kilowatt-hour is also vital when sizing a solar system. For one, it is easier to choose a battery bank with sufficient capacity when you know how many kilowatt-hours all the solar devices will consume.

For instance, if all the solar devices have a total wattage of 0.3 kW, and you intend to run them for 10 hours daily, their total kilowatt-hours (kWh) per day would be 0.3 x 10 = 3 kWh.

Knowing that the daily energy usage of the solar devices is 3 kWh, you’ll know to get a battery bank with a capacity of at least 3 kWh.

Of course, when you have an idea of the capacity of the battery bank you are getting for the solar power system, you can estimate the number of solar panels to get.

How to Convert Watts to Kilowatt Hours (W to kWh)

Watts to kWh Formula

To convert watts to kilowatt-hours, we must convert watts to kilowatts first. Here’s the formula for that:

kilowatts = watts/1000 (1)

Then to finally convert kilowatts to kilowatt-hours, we’ll multiply kilowatts by hours:

kilowatt-hours = kilowatts x hours (2)

Using an electricity bill calculator/watts to kWh calculator would compress these two steps into a single step. To get the formula for that single step, we’ll substitute kilowatts for watts/1000 in (2).

So, instead of converting watts to kilowatts then kilowatts to kilowatt-hours, we’ll have the following:

kilowatt-hours = watts x hours ÷ 1000 (3)

So, we can convert watts to kilowatt-hours by multiplying watts by hours then dividing by 1000. This is what a W to kWh calculator does.

Watts to kWh Conversion Examples

Example 1

How much energy will a 2 W solar radio use if it keeps running for 5 hours?

This is a simple one; all we have to do is multiply watts by hours then divide by 1000:

= 2 x 5 ÷ 1000

= 0.01 kWh

Example 2

A ceiling fan rated 220 volts and 1 amp stays on for 8 hours. How much energy (in kilowatt-hour) would it have consumed within the period it stayed on?

This is not as straightforward as the first example because the wattage of the fan was not provided. But since we know the fan’s voltage and amperage, we can calculate watts.

The wattage of the fan:

= 220 x 1 = 220 W

Now, the energy consumption of the fan for 8 hours:

= 220 x 8 ÷ 1000

= 1.76 kWh

Example 3

A 300 W solar refrigerator runs for 8 hours on Tuesday, 6 hours on Wednesday, and 9 hours on Thursday. How much energy did it consume over those 3 days?

This is pretty straightforward. All we have to do is multiply the wattage of the refrigerator by its total running hours for those 3 days. Then we’ll divide by 1000.

Total running hours = 8 + 6 + 9 = 23 hours

Energy consumption in kWh = 300 x 23 ÷ 100

= 6.9 kWh

Watts to Kilowatt Hours Conversion Chart

Watts (W)

Kilowatt–Hours After 6 Hours (kWh)

Kilowatt–Hours After 12 Hours (kWh)

Kilowatt–Hours After 24 Hours (kWh)





























How Do I Convert My Energy Consumption of Kilowatt-Hours Into Watts?

We can convert energy consumption of kWh to W by adjusting the formula we used for watts to kilowatt-hours (kWh) conversion. But instead of making kilowatt-hour the subject of the formula, we’ll make watts the subject:

kilowatt-hours = watts x hours ÷ 1000

watts = kilowatt-hours x 1000 ÷ hours


What’s the power consumption (in watts) of a ceiling fan if it consumes 1 kWh of energy when it runs for 6 hours?

the power consumed by the fan over 6 hours = 1 x 1000 ÷ 6

= 166.7 watts

Are Kilowatt-Hours Different Than Kilowatts?

Yes, kilowatt-hours and kilowatts are different units. While kilowatt-hours is a unit for measuring electrical energy, kilowatts is for measuring electric power.

How Many Kilowatts Should a Generator Be to Run a House?

The ideal kilowattage of a generator needed to run a house ultimately depends on the total wattage of all the appliances in the building.

For instance, if the total load in your building is 5 kW, you need a generator with a kilowattage greater than 5 kW. Typically, the generator’s kilowattage should by 25% higher than the total load. So, for the 5 kW building, the generator should be at least 6.25 kW.

What Does One Kilowatt-Hour of Electrical Energy Cost?

The cost of one kilowatt-hour of electrical energy varies across the states. But you can expect to pay anywhere between 10 and 30 cents for one kWh of electrical energy in the United States.

Knowing how much you pay per kilowatt-hour of electricity in your area can be pretty helpful. For one, you get a sense of how much money you can save when you move some of your load to a solar power system.

Apart from that, if you ever have to cut down your electricity bill by a certain amount, you can readily figure out how many kWh to cut out of your energy usage.

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