Watt Hours to Watts (Wh to W) Conversion Calculator

What Is Watt-Hour (Wh)?

Watt-hour (Wh) is a unit typically quantifying how much electricity is used or produced in an electric circuit. It measures the energy usage or generation resulting from consuming or generating a certain amount of power over a given number of hours.

Going by the definition of watt-hour, one watt-hour would result from consuming or producing one watt of power for one hour. Similarly, two watt-hours would come from consuming or generating two watts for one hour.

Watt-hour is a derived unit, a combination of the units of power and time. In other words, watt-hour is not one of the international systems of units (SI units).

What Is Watt (W)?

Watt is the SI unit of power. It quantifies energy consumption or generation per unit of time.

Regarding electricity, watt would typically quantify electrical energy usage or production (in watt-hour) per hour.

How to Convert Watt Hours (Wh) to Watts (W)

Watt-hour to Watts Calculation Formula

Watts-hour to watts conversions are pretty straightforward. So long we have the time period of the energy use or production, they can be done in a single step.

To calculate watts from watt-hour, all we have to do is divide the value of watt-hour by the time period (in hours):

\(watts\ (W) = \displaystyle{\frac{watt\mbox{-}hour\ (Wh)}{hour}}\)

Example 1

So, if we have a solar panel that generates 288Wh of energy when exposed to the sun for 6 hours, what would be the average solar power generation of the panel?

Going by the watt-hours to watts conversion formula, the average power generation of the panel would be:

\(\displaystyle{\frac{288}{6}} = 48\ W\)

Example 2

If you car fan runs on solar power and consumes 40 watt-hours of energy when it runs for 8 hours, what is the wattage of the fan?

The wattage of the car fan is:

\(\displaystyle{\frac{40}{8}} = 5\ W\)

Watt-Hours to Watts Quick Conversion Chart

How to Calculate Watt-Hours of an Appliance

Calculating the watt-hours of an appliance requires just two quantities: wattage (power consumption) and time (period of power consumption).

Once we have those two quantities, we can determine an appliance’s watt-hours by multiplying them.

So, if we have a 5 W solar radio, and we leave it on for 3 hours, it would have consumed:

\(5 * 3 = 15\ Wh\ of\ energy\)

While most devices come with their wattage clearly stated, some don’t. So, how can we estimate the watt-hours of such a device? We can calculate the watt-hours of such devices using their voltage, current, and hours of energy use.

Say we have a solar lamp post drawing 0.75 amps of current from a 12v battery voltage for 3 hours. How much energy would the battery discharge within that period?

\(volt * amp * hour = 12 * 0.75 * 3\)

\(= 27\ Wh\)

Why Calculate Watt Hours?

Calculating watt-hours for all your devices helps you estimate and forecast your energy consumption. This way, you can adjust your electricity usage to the desired level on your energy bills. In other words, you might be able to reduce your utility bills with a little ease when you know how much electricity each of your devices consumes.

For instance, you can replace incandescent lightbulbs with LED lightbulbs. Since LEDs consume less energy, they’d bring your total watt-hours down.

Of course, you may be unable to replace or stop some energy-intensive devices. But you might be able to limit their hours of usage.

When pulling power from a finite source, the total energy you can pull from it is limited. By calculating watt-hours for your devices, you can carefully combine them to maximize the power from the power source.

Say you have a solar generator whose battery capacity is 288 Wh. If you try connecting devices with a total energy usage of 300 Wh (for one hour) to the solar generator, it won’t last up to an hour. It may even get overloaded.

Of course, both situations are undesirable. But you can avoid them if you already know how much energy all your devices consume when used together.

How to Convert Watts to Watt-Hours

To convert watts to watt-hours, all we have to do is multiply the value of watts by the number of hours of power consumption or generation:

\(watt\mbox{-}hour\ (Wh) = watt\ (W) * hour\ (h)\)

Example 1

How much energy does a 1.2W solar disk light consume if it stays on for 8 hours?

Energy consumed by the solar disk light over 8 hours would be:

\(1.2 * 8 = 9.6\ Wh\)

Example 2

Let’s convert watts to watt-hours for a 2.4W lamp post running for 12 hours:

\(2.4 * 12 = 28.8\ Wh\)

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

Converting watts to kilowatt-hours is similar to how we convert watts to watt-hours. However, because kilowatt-hours measure at a magnitude 1000 times higher than watt-hour, we must divide the value of watt-hour by 1000.

So, if the formula to convert watts to watt-hour is:

\(watt\mbox{-}hour = watt\ (W) * hour\ (h)\)

The formula to convert watts to kilowatt-hour would be:

\(kilowatt\mbox{-}hour =\displaystyle{\frac{watt\ (W) * hour\ (h)}{1000}}\)

So, if a solar street light uses 15 watts for 5 hours, its energy consumption would be:

\(\displaystyle{\frac{15 * 5}{1000}} = \displaystyle{\frac{75}{1000}} = 0.075\ kWh \)

How to Convert Watt-Hours (Wh) to Kilowatt-Hours (kWh)

To convert Wh to kWh, all we have to do is divide watt-hour by 1000:

\(kWh = \displaystyle{\frac{Wh}{1000}}\)