An Ultimate Guide To Know What Is The Capacity Of A Water Heater Measured In

Undoubtedly, water heaters don’t require a formal introduction here. The majority of the households are equipped with water heater today. It may be an electrical water heater or a gas water heater. But it is surprising that many of us know a very little about the water heater that we have at our home.


So what should one know about their water heaters? Well, there are the basics. A well-informed user must know every minute detail about the water heater which is related to its consumption. You must know about its wattage, its mode of operation and so on.

In addition, you should also know about the capacity of your water heater which would help you in making the best use out of it. So do you know, what is the capacity of a water heater measured in? Fret not, we just got you covered! Read the article further to find out.

Unit For Measuring Your Water Heater Capacity

In order to determine the capacity of the water heater, it is essential to know how the capacity of the water heater is measured. Depending on the country you are from and the system of measurement used there, the capacity of your water heater can be measured in 2 ways.

Since the United States of America follows the metric system, the capacity of the water heater is measured in gallons whereas the rest of the world follows the imperial system and use liters as the unit of capacity.

How Can You Know Your Water Heater’s Capacity?

If you are a responsible adult in your household, it is essential for you to know your water heater’s capacity, especially when you have electrical and plumbing issues in your house. It also makes it an easier task when it comes to replacements.

You can easily find out the capacity of your water heater by checking the specifications plate available on it. The specification plate also provides you with other information about the water heater, like its power requirements and the likes.

How To Select The Right Capacity Of Water Heater?

It is important to know how much water your water heater is capable of holding. If the capacity of your heater is less than your requirement, you could find a shortage of warm water. And if the capacity of your water heater is more than your daily requirement, then you could be wasting a lot of energy.

Here are a few factors that would help you in making a balanced decision.

Estimate the space available for water heater installation

It happens when you don't estimate the space available for water heater installation

The amount of space available is essential in order to determine the capacity of the water heater. Depending on the size of the water heater, they can be divided into two types, short water heaters also called “short boy” and tall water heater which are also called “tall boy”.

The short water heaters are ideal where space is minimal. They have shorter height but are wider than their tall counterparts which make them suitable for spaces with limited headroom like crawl spaces and under cabinets.

These water heaters can be between 30 to 49 inches in height and can hold up to 50 gallons of water at a time.

Their taller counterparts are more suited for large open areas that have a lot of headroom.

These can be as tall as 76 inches and can hold up to 100 gallons for water at a time. They are best suited for large spaces like garage or basement which can also provide space for all its wirings.

Determine the right capacity of water heater for your household

In order to calculate the right capacity, here are a few steps you need to follow:


Analyze the peak hour of hot water demand in your house. Is it at 7 am when all your family members take bath? Or at 8 am when your washing machine is operating simultaneously along with a dishwasher?


Once you have the peak hour with you, calculate the individual water usage in each activity and add them up. Here is a rough chart to help you out:

  • Water used in shower: 10 gallons per person
  • Water used in laundry: 30 gallons per use
  • Water used is dishwasher: 15 gallons per use

Calculate all the other water requirements the same way, and add them up. This would roughly give you an estimate of the required capacity of the water heater.

Wrapping Up

It is important to have an idea about the specification of your water heater and all your appliances for easier repair and replacement. Did you already know the capacity of your water heater? Let us know in the comments.

Abigail Jones

Hi, I'm Abigail. I like spending time tearing my house apart and putting it together back again. Join me on home improvement tutorials, tips on my blog.

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