How to Calculate Washing Machine Capacity? (With formula)

When buying a washing machine, it is important to calculate the capacity to ensure it is big enough for your needs.

The capacity of a washing machine is typically measured in kilograms, and you will need to know the weight of your laundry in order to calculate the capacity.

While there is a lot of formula involved to calculate the capacity of the washer, you can try using the below method. 

The simplest way to calculate the capacity of the washer is to multiply the weight of your laundry by the number of loads you plan to wash. For example, if you have 2 kilograms of laundry and you plan to wash three loads, you will need a washing machine with a capacity of 6 kilograms. It is also important to keep in mind that the capacity of a washing machine will vary depending on the type of machine.

Front-loading washing machines tend to have a larger capacity than top-loading machines. Therefore, if you have a large amount of laundry, it is best to choose a front-loading machine.

When we talk about washers’ capacity, it simply refers to the washtub’s capacity where you add your clothes along with water and detergent.

So, before you add any load to your washer, it is of utmost importance to know its holding capacity to prevent unavoidable damages. Loading fabrics below their capacity is absolutely fine, make sure not to exceed their maximum capacity.

How to Calculate Washing Machines capacity?

The washer’s capacity is calculated in Kilograms (KG) or Cubic Feet (cu. ft.). Therefore, calculating the capacity of the washer via Kilograms or pounds would be easier in layman’s terms. It is quite simple, for e.g. a washer holding a 7KG capacity can wash fabrics weighing up to 15 to 16 pounds.

Note: The weight is considered for dry fabric.

Mathematically the capacity of the washer is calculated via Cubic Feet (cu. ft.) which we will discuss further in this topic.

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Formula to calculate the washer’s capacity

There’s a geometrical formula available to calculate the tub capacity of a washer:

Volume (cu.ft.) = Pi x radius x radius x height

Refer to the image below for supporting the calculations:

As per the above image, the calculation will look simple. In words, it will be Pi (ℼ) of radius square (r²) multiplied by height (h).

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How to calculate the tub volume?

The radius (r) can be measured from the center of the washtub towards the covering wall. Another way to figure out the radius length would be simply to measure the diameter and divide it by two. 

Then multiply the radius length with the same number (get the square of the radius, e.g. if the radius is 1.2 feet then multiply 1.2 X 1.2). 

Finally multiply the value by the depth of the tub which is its height (h), to find the capacity or the volume of the washer.

Average washtub sizes range from 2.5 cubic feet to 3.5 cubic feet in most models. The load capacity of a washer is determined by its size, hence you need to be specific in choosing a suitable size depending on the size of your laundry. Basically, a cylindrical volume formula is used to calculate a washer’s size due to its appearance.

You may calculate the capacity of the washer through the below steps: explained numbers.

Step 1: Using a measuring tape, determine the depth or the height within the washtub. Measure from the back to front of the washtub in case of a front loader, and for a top loader measure from the bottom of the tub to the top.

Let us assume that a washer has a height/depth of 1.8 feet. (h = 1.8).

Assuming the height has been measured now you need to get the radius measured, let us proceed to the next step.

Step 2: To get the radius figured out, let us measure the washtub’s diameter which is the length of the tub from one end to the other. Let’s assume the diameter is 1.8 feet long. Divide this figure by 2 (1.82 = 0.9). Now you have the radius calculated which is 0.9 feet. (r = 0.9)

Step 3: Square the radius value (0.9)². You can get the square value by multiplying the number with the same value (0.9 X 0.9 = 0.81). Now we have the r² value. (r² = 0.81)

Step 4: Multiply the radius square value with the height (r² x h) i.e. 0.81 multiplied by 1.8 = 1.46.

Step 5: To calculate the capacity, multiply the number calculated in Step 4 by Pi ( x 1.46 = 4.58). Now you have got the value of Pi which is 4.58 (considered as 4.6 cubic feet)

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What is the average capacity of a washer?

Washers differ in various capacities such as; the compact top load washers hold a capacity anywhere around 2.30 – 2.45 cu ft, the standard, and high-efficiency top-loaders range from around 3.1 – 4 cu ft. If you are hunting for a larger capacity washer, you may opt for the front loaders as they hold a capacity of around 4 – 5 cu ft.

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What size washer do I need for a family of 4?

You may determine the size of the washer by your laundry needs on a regular basis. For a family of 4, on average you may consider a washer with 4 cubic feet capacity. As it may easily hold up to 16 pounds of laundry in a single wash.

A household with more than three can opt for a 4 cu ft to 4.5 cu ft washer depending on the laundry requirements. However, you may consider a smaller-sized washer depending on the quantity of laundry used on a regular basis.

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What size washer is needed to wash a king-size comforter?

To wash a king-size comforter you will need a washer size of at least 4.2 cubic feet or more. Washers with 4.2 cu ft can wash up to 16 to 18 pounds of laundry which is a good number in terms of holding the fabric’s weight.

Can you wash a king-size comforter in a 4.5 cu ft washer?

Yes, you can easily was a king-sized comforter in a 4.5 cu ft washer. A washer capacity of 4.5 cu. ft can hold up to 20 pounds of laundry in a single wash. Such washers are usually suitable for larger families or for the ones who do excess laundry. 

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How many towels can you wash in a 4.5 cu ft washer?

Washers with a 4.5 cu ft holding capacity can be termed as a medium-size washers. It can wash anywhere between 16 to 20 pounds of laundry, which means around 10 regular-sized bath towels can be easily washed.

You may add more towels however, it is always a good idea to leave enough room for movement. 

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How much can you fit in a 3.5 cubic foot washer?

A 3.5 cubic feet tub can wash up to 12 to 15 pounds of laundry. It also depends on what fabrics are used during the wash cycle. This measure can fit a queen-size comforter in your washing machine.

Final thoughts

Choosing the size of the washer is not always challenging as one may not be limited to the same amount of laundry on a regular basis.

On a few occasions such as festivals and family gatherings during the holidays, there may be an increased load on your washer, but that is perfectly normal.

In such scenarios, it’s best to repeat the wash cycles to complete the entire load.

Lastly, don’t get into the complexity of calculating washers, as in real life these calculations do not work since the laundry load will vary on a daily basis.

For more information related to your laundry do visit our FAQ section.

Also Read: How to bypass the water level sensor in a washing machine?

Manish Singh is an expert in electrical engineering with a Diploma in the field. With over 12 years of experience, he specializes in repairing music systems, washing machines, dryers, and other laundry-related appliances. His in-depth knowledge in electrical repairs and decent knowledge about garment care makes him a trusted authority in the field of appliance repair and laundry related topics. If you have any questions or need assistance with your appliances, you can reach out to Manish through email: manish.singh (at)