Difference between Soap and Detergent

Soaps and detergents are both cleaning products that help clean or remove dirt, germs, and other unwanted particles from the human body and other surfaces. Because both are used for cleaning purposes, people often get confused between these two cleaners and use these terms interchangeably. However, in reality, there are significant differences between soaps and detergents.

Difference Between Soap and Detergent

Before discussing the difference between soap and detergent, let’s have a quick overview of both:

What is Soap?

Soaps are prepared by the reaction of alkali (i.e., sodium hydroxide) with naturally occurring fatty acids. This reaction helps to produce sodium salts of the fatty acids used, which ultimately makes cleaning more efficient by allowing water to remove greasy stains from surfaces. The soap's primary ingredients are natural, such as vegetable oils and animal fats. However, major-branded soaps may contain additional chemicals for particular colors and fragrances.

The first and most common process of soap production is the saponification of oils and fats. The second method involves neutralizing fatty acids with alkali. Since soaps are natural, they can also be made at home using clean glycerine, essential oils, herbs, and some spices, etc. In addition, soaps are biodegradable due to natural ingredients. This means they are comparatively less harmful to the environment than traditional synthetic cleansing products.

Characteristics of Soap

The following are the main characteristics of Soap:

Soap is defined as potassium or sodium salts of carboxylic acids, which are accompanied by a long aliphatic chain.
Soaps are generally called surfactants; this means that they can help reduce the surface tension between the liquid and other substances. It is beneficial in the process of emulsification of various oils in water. 
Soap is mainly produced using the saponification process between fats and oils.
The two ends of the soap molecule, the carboxylate end, and the hydrocarbon end, are hydrophilic and hydrophobic.

What is Detergent?

A detergent is usually defined as a surfactant or the combination of multiple surfactants having cleaning properties in a dilute solution with water. Like soaps, detergents are also called amphiphilic, which means that they also contain hydrophobic and hydrophilic regions. In most cases, detergents are akylbenzenefulfonates. Detergents tend to easily get dissolved in hard water because detergents sulfonate does not attach to calcium and other ions in hard water.

Typically, detergents are produced by mixing different chemical compounds; then by heating the mixture and following certain measures, the powder is dried in detergent form. The produced detergents can then be used for several years. The chemical compounds used in the production of detergents usually include from Dioxide, Phosphates, and Surfactants (commonly used by mainstream detergent manufacturers) to Salt and Citric Acid. To produce detergent in liquid form, the mixture contains a high amount of water.

Characteristics of Detergent

The following are the main characteristics of Detergent:

Detergents are defined as potassium or sodium salts of a long alkyl chain with a sulfonate group at the end.
Detergents are known for their easy soluble property in hard water.
The sulfonate group present in the detergent does not attach itself to hard water ions, making it soluble in hard water.
Anionic detergents like alkyl benzene sulfonates are commonly used for domestic purposes.

Difference Between Soap and Detergent

Soap vs Detergent: Key Differences

Let’s discuss some major differences between soaps and detergents:

When it comes to production, soaps are prepared using natural ingredients while detergents are synthetic, man-made derivatives.

The molecule of soap is usually a carboxylate ion while common detergents often consist of phosphate or sulfate head-groups (sodium dodecyl sulfate).

Soaps do not easily dissolve in hard water. Detergents, on the other hand, dissolve easily in hard water.

Soap allows cleaning for limited applications, while detergents can be produced according to a variety of cleaning applications.

Soap has a weak cleansing action, while detergents have a better and stronger cleansing action.

The head-group of the soap molecule is a typical carboxylate anion. However, common detergents often use phosphate or sulfate head-groups (e.g., sodium dodecyl sulfate).

Difference Between Soap and Detergent

Let’s discuss the difference between soap and detergent with the help of the following comparison chart:

Soap Detergent
Soap is sodium or potassium of a carboxylic acid that is attached to a long aliphatic chain. Detergent is usually a sodium or potassium salts of a long alkyl chain that terminates with a sulfonate group.
Soaps are produced using natural ingredients, such as vegetable oils and animal fats. Detergents are produced using synthetic resources, such as hydrocarbons of coal or petroleum.
Since soaps are prepared using natural ingredients, they are easily biodegradable. Some detergents are biodegradable. Detergents containing branched hydrocarbon chains are not easily biodegradable.
Soaps usually take time to get dissolved in water. Detergents take less time and dissolve faster in water.
Soaps do not dissolve in hard water and saline water. That is why soaps are not effective in hard water. Detergents tend to get dissolved in both soft water and hard water. This makes detergents effective in both types of water.
Soaps typically form scum when used in a hard water environment. Detergents include compounds that do not form scum issue in any type of water.
Soaps are not much reactive and have weak cleansing action. Detergents are more reactive and have strong cleansing action.
Soap is said to be environmentally friendly. Detergents are compounds that can form thick foam that causes the death of aquatic life.
Soap can sometimes cause skin irritation. Detergents do not usually cause skin irritation.
Soaps are used for limited cleaning applications, such as body parts. Detergents are used for a variety of cleaning applications, such as laundry, dishwashing, and other types of surface cleaning.
Some of the most common examples of soap include sodium stearate, sodium palmitate, and sodium oleate. Some of the most common examples of detergents include deoxycholic acid and sodium lauryl sulfate.

How does a cleaning process for soaps and detergents work?

The concept of a cleaning process is almost the same for both soaps and detergents. We can explain step by step process of cleaning using the following four points:

First, the surface or a body that needs to be cleaned is moistened using water.

Next, soap or detergent is applied to the surface that is absorbed. Because both soaps and detergents are known as surfactants (or surface-active agents), the surface-active molecules that exist in soaps and detergents dissolve in water. This ultimately helps to weaken the surface tension, the applied force, that attaches molecules to a surface. As a result, water is easily spread on a surface or soaked in a cloth.

When the surface is rubbed, dirt particles present on the surface break down as surface-active molecules work to separate the dirt from the surface and attach them to the water. The same rule works with clothes.

At last, dirt particles are coated with molecules of soap or detergent, preventing them from re-attaching to the surface. This eventually causes dirt particles to be suspended in water until the dirt is completely washed away. 


Both soap and detergent are intended to help clean up, but there are differences in their production process and quality of cleaning. While soaps are based on natural ingredients, detergents are prepared with synthetics and are man-made derivatives.

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