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How Does the Washing Machine Sense Load Size

Interior Of Home Laundry Room With Modern Washing Machine

Washing machines are smarter than ever. Many machines can now sense the optimum water for your clothes, saving water and money. How is this possible?


The washer senses the size of the load with a displacement sensor. This is located in the shock absorbers in most models.

The displacement sensor measures the weight of the clothes during spinning. Then, it estimates how full the tub is based on this data.

Keep reading for answers to all of your questions. What is a displacement sensor? How accurately can a washing machine predict load size?

What Is a Displacement Sensor?

Clothes In Washing Machine

A displacement sensor is a device that measures the force by being compressed. This force is most often expressed in PSI or weight.

These sensors are used in many common everyday devices, such as bike pumps, bathroom scales, and washing machines.

How Washing Machines Sense Load Size

Your washing machine contains a small set of sensors called displacement sensors connected to your computer (sometimes colloquially called the appliance’s “brain”).

These sensors and the attached computer must go through several steps to sense load size.

1. Initial Spin

Internal View Of A Washing Machine Drum During Wash

The washer begins sensing the load size as soon as you press start. If you watch your machine, it will turn back and forth without adding any water.

This allows the clothes to press against the size of the tub, activating the displacement sensors.

The sensors will record the force of the clothes on the tub’s sides, which estimates how heavy a load of clothing is.

Sometimes, the washer will soak the clothing first before spinning. This makes it heavier and easier for the sensors to pick up.

2. Data Analysis

Beautiful Young Woman Sits On Her Knees Next To The Washing Machine

Once these initial spinning motions are completed (up to three minutes), the data collected by the displacement sensors is sent to the washing machines’ computers.

The computer will then analyze the data by plugging the number into a pre-programmed equation. The equation is designed to estimate the volume of clothing based on its measured weight.

3. Decision

Asian Housewife Put Clothes Into Washing Machine Happily At Home

The computer will then solve the equation, telling it how much water to use. It then carries out that decision using the fill function of the machine.


Washing machines use a simple but clever method to estimate the load size of each wash. They employ a sensor that measures the weight of the clothes.

Then, a simple computer puts this number into an equation and tells the fill function on the machine how much water is needed.

Frequently Asked Questions

How Accurately Can a Washing Machine Sense Load Size?

The washing machine typically senses load size with enough accuracy to prevent problems. However, it is not perfect. Some fabrics weigh slightly more than others, making the sensing methods inexact.

Can the Washer Overflow if the Load Size Sensor Isn’t Working?

In rare cases, the load sensor failing can cause the machine to overflow. However, most units also have a sensor that turns the water off if the level gets high enough.

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