How Many Watts Does a Water Heater Use?

When you’re enjoying a hot shower or relaxing in a warm bath, you’re probably not thinking, “How many watts does a water heater use?” But knowing how much electricity is being used by one of your household’s most important appliances is helpful when it comes to improving energy efficiency and managing utility costs. 

If you need help calculating your water heater’s energy use or want to replace it with a more energy-efficient model, hire a local water heater contractor to get the job done. Let’s review the wattage used by a water heater and how to use that information to your advantage.

Average Wattage Used by a Water Heater

To find out how many watts your water heater uses, it’s easiest to look directly at the tank to read the wattage and other energy information printed on the label. Otherwise, here are some guidelines:

• 10–20-gallon water heater: 1,000–2,000 W (1,600W average)

• 30–80 gallon water heater: 4,500 W 

Even though residential water heaters range in size, those in the 30-80 gallon range typically use the same wattage, 4,500W. That’s because wattage is not based on the capacity of the tank, but the energy needs of the heater itself.

What Is a Watt?

If you need a refresh on watts (W), it’s a basic measuring unit of energy primarily used to calculate larger volumes of electrical power. A watt equals an amount of energy for one second. For context, a typical home wattage is between 1,083 to 1,375 watts.

When discussing and measuring an appliance’s power consumption, we typically refer to its energy needs in watts. If we measure the amount of energy a device needs to operate for an extended period, such as a week or a month, we use kilowatt-hours (kWh). Keep these definitions in mind when evaluating your water heater’s energy consumption.

How Much Does It Cost to Run Your Hot Water Heater?

Your water heater is one of the biggest energy users in your home. Aside from heating water for your shower or bath, it also supplies hot water to your faucets, washing machine, and dishwasher. Keep in mind, though, that unlike an air conditioner or other appliance that might run during the majority of the day, your hot water heater will run about two hours per day. Based on that average, let’s figure out how much running your water heater costs.

You are charged by the kilowatt hour on your electric bill, so let’s see how many kilowatt hours a 4500W water heater needs to run:

Wattage x Number of operating hours / 1,000

4500W x 2 (hours) / 1,000 = 9 kWh

That means your hot water heater needs 9 kWh to run each day, or around 270 kWh to run per month. According to EnergySage, the average cost for electricity is $0.23 per kWh. Let’s do the math:

4500W: $0.23 x 270 kWh = $62.1 per month, or about $2.07 per day

How to Lower Your Water Heater’s Energy Costs

Even though your water heater costs a little more than a dollar an hour to operate, there are ways you can conserve energy and save money on your electric bill each month. Follow these tips and tricks to save on your water heater’s utility costs.

• Replace your current water heater with a more efficient model: You could opt for a tankless water heater, which provides hot water when needed rather than store it up for later use. This type of model uses less energy and it also takes up less space. But if you prefer a more traditional water heater, newer models—especially those with the ENERGY STAR®  label—will run more efficiently.

• Add a timer: Set a schedule for your water heater to run only when you need hot water. You can call a professional plumber or a water heater contractor to install one on your current hot water heater.

• Insulate your water heater: The water needs to be heated, not the rest of the room or basement. Wrap your heater in insulation or some type of thermal cover that will keep that heat from radiating outward.

• Stick to a maintenance schedule: It’s important to have your household’s major appliances and systems repaired or serviced regularly to prevent future issues and troubleshoot current ones. For your water heater, this means draining or flushing the tank to remove any build-up that could prevent it from working properly.

• Lower the thermostat: Decreasing the water heater’s temperature will naturally result in water that isn’t quite so hot, but it can add up to savings.

• Do full loads of laundry and dishes: By running these appliances only when full, you’ll save energy. Also, consider using a cold or warm setting as opposed to hot to give your water heater a break.

• Limit your shower time: If you get your best ideas in the shower and prefer to linger, then it’s a good idea to replace your current shower head with a low-flow one.