Watts and watt-hours can be confusing, but understanding the difference is key to managing your energy consumption.
A watt (W) measures power, which is the rate at which energy is used. A watt-hour (Wh) measures energy, specifically the amount of energy consumed over a period of time.
Knowing how watts and watt-hours relate to each other helps you understand how much energy your devices use, which can help you save money on your electricity bill. It’s also super helpful for planning battery use for portable devices or off-grid power systems.
This article will explain how to calculate watt-hours from watts and how to calculate watts from watt-hours. We’ll also look at practical examples with common appliances and batteries, and of course, show you a watt hours to watts calculator.
Understanding Watt-Hours
Before we dive into calculating, let’s clarify what a watt-hour actually is.
What is a Watt-Hour?
A watt-hour (Wh) is a unit of energy. To get technical, one watt-hour equals 3,600 joules. In simpler terms, it’s the amount of energy a one-watt device uses when it’s running for one hour.
It’s important to understand the difference between energy and power. Power, measured in watts, is the rate at which energy is produced or used. Energy, measured in watt-hours, is the capacity to do work.
Why Calculate Watt-Hours?
Knowing how to calculate watt-hours is useful for a few reasons. It helps you estimate how much energy your appliances are using, choose the right size battery for your devices, and get a better handle on how to reduce your energy use and lower your bills.
How to convert watts to watt-hours
The formula for converting watts to watt-hours is pretty simple:
Wh = W × hrs
That means watt-hours equals watts multiplied by hours.
To perform the conversion, just follow these steps:
- Figure out how many watts your device uses.
- Determine how many hours you plan to use the device.
- Multiply the wattage by the time to get the watt-hours.
For example, if you run a 50-watt fan for 3 hours, you’ll use 150 Wh.
50 W 3 hrs = 150 Wh
Calculating watt-hours for appliances
Most appliances list their energy usage on a label somewhere on the appliance itself. It’s usually listed in watts (W), but you may see amperage (A) and voltage (V) instead.
If your appliance lists amps and volts, you can calculate watts using this equation:
W = A × V (Watts equals amps multiplied by volts)
In the U.S. and Canada, standard voltage is 120V.
Example calculation
Let’s say you have a blender that uses 12 amps at 120 volts. Its wattage is 1440 watts, because:
12 A 120 V = 1440 W
If you run that blender for 0.5 hours (30 minutes), it will consume 720 watt-hours, because:
1440 W 0.5 hrs = 720 Wh
Using electricity usage monitors for accurate measurements
For a more precise reading, you can use an electricity usage monitor. These handy gadgets give you an accurate watt-hour measurement for each appliance you use.
To use one, simply plug the monitor into the outlet, then plug your appliance into the monitor. The monitor’s display will show you exactly how many watt-hours the appliance is using.
Calculating Watt-Hours for Batteries
Watt-hours (Wh) measure how much energy a battery can store. Think of it as the battery’s “fuel tank” capacity.
To calculate watt-hours, you’ll need to know the battery’s amp-hours (Ah) and voltage (V). Use this formula:
Wh = Ah × V
For instance, a 12V car battery with a 50Ah rating has a capacity of 600 Wh. (50 Ah 12 V = 600 Wh)
How to convert watt-hours to watts
The formula is simple: W = Wh / hrs (Watts equals watt-hours divided by hours).
Here’s how to do it:
- Find out how many watt-hours your device used.
- Figure out how many hours you used the device.
- Divide the watt-hours by the number of hours.
For example, let’s say your TV uses 196 watt-hours in 2 hours. That means it consumes 98 watts of power. (196 Wh / 2 hrs = 98 W)
How to convert watts to kilowatt-hours
A kilowatt-hour (kWh) is a larger measurement of energy that equals 1000 watt-hours. Utility companies use kWh to measure your household energy consumption.
The formula to convert watts to kilowatt-hours is:
kWh = (W × hrs) / 1000
Here’s an example: A 500-watt refrigerator that runs for 24 hours consumes 12 kWh.
(500 W 24 hrs) / 1000 = 12 kWh
How to use watt-hours in real life
Understanding watt-hours is useful in many situations. For example, you can use watt-hours to calculate the right battery size for a camping trip. You can also use watt-hours to estimate how much it costs to run your appliances.
Here are a few tips for saving energy:
- Replace old-fashioned incandescent light bulbs with LEDs, which use about 75% less energy.
- Unplug electronics when you aren’t using them.
- Choose energy-efficient appliances.
To Conclude
To recap, remember these essential formulas: Watt-hours (Wh) = Watts (W) x Hours (hrs); Watts (W) = Watt-hours (Wh) / Hours (hrs); and Kilowatt-hours (kWh) = (Watts (W) x Hours (hrs)) / 1000.
By understanding these conversions, you can better manage your energy consumption, make smart choices about energy usage, and lower your carbon footprint.