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How Many Watts Does a Hot Water Heater Use?

Writen by Ronald Brown

Fact checked by Natalie Bridges

How Many Watts Does a Hot Water Heater Use

Are you wondering if your water heater is giving you the energy savings it promised? Learning how many watts does a hot water heater use is one of the most crucial steps to determining how much you are spending on water heating every year.

This information also allows you to make energy-conservation measures without giving up on using hot water in many household and personal activities. It can pave the way for purchasing a more energy-efficient and cost-effective water heater for your home.

Table of Contents

Number of Watts Required to Operate a Water Heater


The majority of electric water heaters use anywhere between 4500 watts and 5500 watts as a dedicated 240-volt electrical system. These devices typically have two heating elements that allow for a quicker recovery rate.

A hot water heater’s recovery rate reflects its ability to provide hot water within a given period of time.

For example, the 4500-watt A.O. Smith ENS-50 ProMax 50-gallon electric water heater has an industry-leading recovery rate of 21 gallons per hour. By comparison, the 50-gallon, 4500-watt Rheem MR50245 Marathon only provides 20 gallons per hour.

Some water heaters have a lower power rating, ranging from 1500 watts to 3000 watts. These units come with a single element and run on 120-volt systems, mostly requiring about 1,125 watts to operate. They are ideal for households with modest hot water needs.

If you have a two-element water heater, check the specifications label. Most manufacturers put the power rating for each heating element. However, do not combine both elements’ power ratings to determine the water heater’s total energy consumption.

For example, suppose your two-element water heater says it consumes 4,500 watts. It would be best not to think that your water heater will use 9,000 watts. Its maximum power consumption is still 4,500 watts.

How to Find the Correct Water Heater Wattage Information

Your water heater has a label containing specifications and other vital information, including its power rating. You should see this label on your water heater’s side, typically near the heating element panel.

The label shows your water heater’s wattage and operating voltage. As already mentioned above, if your unit works on a 240-volt system, you can expect two elements. Each element will have its wattage rating.

Suppose you cannot find the wattage information on the label. In that case, you may have to look for the current operating rating expressed in amperes. Multiply this number with the voltage rating to determine your unit’s wattage rating.

For instance, a 240-volt 18.75-ampere water heater will have a wattage rating of 4,500 watts (240 x 18.75 = 4,500).

Suppose these pieces of information are unavailable on your water heater. In that case, the US Department of Energy recommends logging into Energy Star and using its Product Finder feature to obtain helpful information about your water heater.

One issue with using such an approach is that not all water heaters have an Energy Star rating. At least, you will find a more energy-efficient water heater to replace your old unit.

Why Determining a Water Heater’s Wattage Rating Is Important


According to Energy Upgrade California, water heaters are the second most energy-consuming home appliance. Modern homes can use up to 25 percent of energy powering their water heaters, translating to $600 per year on water heating alone.

The US Energy Information Administration places water heating in third place among household electrical appliances that use the most electricity at 12.1 percent.

Knowing your water heater’s wattage rating can help you compute your monthly electric expenditure. You can use this information to make substantial changes in your water heater consumption.

For example, you might want to spend less time in the shower and conserve hot water as much as possible. You can refrain from running the water while brushing your teeth or skip the hot water to wash your dishes in the sink.

Computing Your Annual Water Heater-Related Power Consumption

Since a water heater’s wattage rating impacts your electric bill, it pays to know how much you are spending on water heating every month.

The first step is to determine how many hours you use your water heater every day. You can make a log of your water heater use for seven consecutive days, then take the average consumption. Let’s say you have a daily average water heater use of three hours.

The second step is to multiply the number of hours of water heater usage by your unit’s wattage rating. Suppose you have a 4,500-watt water heater. Using our example above, multiply 4,500 watts by three hours to get 13,500 watts or 13.5 kilowatts per day.

The third step involves multiplying your average daily water heater power consumption by the price of electricity per kWh in your area. If you pay $0.15 for every kWh, you will get an average water heater-related energy expenditure of $2.025 (13.5 kW x $0.15).

If you want to know how much you will pay for the month, you only need to multiply $2.025 by 30 days to get $60.75. In other words, you will be spending about $729 on water heating alone.

Of course, this is only a rough estimate of how much you will be spending on water heating. Your water heater’s total energy consumption depends on the following factors.

Tank Size

The larger the water heater tank, the more energy your water heater consumes to heat your water.

Water Temperature Setting

Heating the water to 110 degrees Fahrenheit requires more energy than setting your device to 100 or 105 degrees Fahrenheit.

Tank Insulation

Heat loss will make your water heater work harder, requiring more energy to deliver the preferred water temperature.

Tank Age

Older tanks are less efficient than newer models.


Determining how many watts does a hot water heater use is an essential step in assessing your water-heating expenditures. On average, water heaters use 4,500 to 5,500 watts per hour, resulting in paying around $500 to $800 annually for water heating.

Notably, water temperature settings and tank size, insulation, and age can all affect your water heater’s energy consumption.

However, you can improve your water-heating energy expenditure by using an energy-efficient model, such as the A.O. Smith ENS-50 ProMax 50-gallon water heater.

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