Laundry Soap vs Detergent: Which Is Better for You, Your Clothes, and the Environment?

You’ve heard the terms laundry detergent and laundry soap before, probably assuming they refer to the same products. I know I did. But it turns out they’re far from the same, each boasting multiple differences.

As soon as I heard they were different cleaning products, I knew I had to dig a little deeper. I had to find out what the actual differences are between these two clothes cleaners. Here’s what I found out.

Laundry soap vs detergent: What’s the difference?

Laundry detergent refers to a marketed product that arose during the first half of the twentieth century during the Great Depression and a series of world wars that made soap a precious commodity. It’s usually full of obscure, hard-to-pronounce, and harmful ingredients that comprise surfactants, dyes, synthetic fragrances, bleach, and sulfates. (Although, to be fair, multiple brands are now attempting gentle, eco-friendly detergent formulas.)

Laundry soap, on the other hand, is usually less mainstream. It’s an all-natural and biodegradable cleaner that’s made by mixing animal fat or vegetable oil with alkali salts and similar natural ingredients to wash away stains. Any fragrances are all-natural essential oils, though the best are fragrance free.

Laundry soaps and laundry detergents are made to do the same thing: clean clothes. They work in essentially the same way, by molecules in the ingredients attaching to the dirt and then rinsing away with the dirt in the water. 

But even though they have the same purpose and work in the same way doesn’t mean they’re the same. Because laundry detergent and laundry soap are distinctly different products, you should know how they’re different before you commit to doing decades of laundry with one or the other. 

The differences can be split into six categories. Let’s dive in.


One of the main differences between soap and detergent is the ingredient list. Soap uses natural and biodegradable ingredients that won’t irritate your skin or harm the environment, including alkalis and lye. 

Detergent, on the other hand, typically uses synthetic and man-made chemicals, such as phosphates, parabens, chlorine, and sodium lauryl sulfate and other substances that increase the water’s surface tension, which helps lift stains from fabrics. These chemicals have a harmful effect on the environment, causing algal blooms and hormone imbalances in aquatic ecosystems. They can also pose a risk to human health. Certain ingredients are more likely to cause cancer and reproductive problems. More often, they can cause skin irritation and allergic reactions, even triggering asthma attacks in some cases.

Luckily, with increased awareness of these issues, many detergent brands are exploring safe, eco-friendly formulas. You can find some of the best in my article about ethical laundry detergents.

Water quality

Soap and detergent perform differently depending on the type of water they’re used in. Soap performs terribly in hard water. It reacts poorly with the chemicals found in hard water, so it can’t do its job properly.

Detergent, however, works well in hard or soft water, so you won’t have a problem no matter what type of water your home has. 

Water temperature 

Water temperature makes a significant difference in how soap and detergent perform.

Soaps need warm water to wash clothes. The hotter the better in this department. If the water isn’t warm enough, there could be some soap scum left over on your clothes. Detergent cleans clothes in any temperature.

Cleaning power

One of the main differences between soap and detergent is how well they both clean clothes. While they’re both designed to do this, the ingredients they use affect their stain removal power.

Detergent is the better option for this, as the ingredients are specifically designed for washing clothes as effectively as possible. As effective as soap is at getting dirt and stains out of clothes, it doesn’t touch the power detergent offers. All those harsh chemicals take out stains like tiny nukes in your laundry room. But you don’t necessarily need them for tough stains. Read my article about laundry detergent substitutes to find out how to treat stains without toxins.


While soap and detergent are designed to do the same thing, the different ingredients they use mean they’ll function differently. Soaps rinse from your clothes better than synthetic cleaners, depending on water temperature and quality of course, and they shouldn’t leave any soap scum residue behind, which can be an issue with certain detergents.

Detergents also have fragrances that cling to your clothes, which can then be absorbed by your skin. If your skin is sensitive, this residue and fragrance cause irritation, and possibly even allergic reaction.


What we put into our washing machines has a significant impact on the environment because that water doesn’t just disappear. It goes into treatment plants, rivers, streams, lakes, and oceans. Laundry detergent is particularly bad for the environment, thanks to its synthetic chemicals. As effective as these are at cleaning clothes, they wreak havoc on waterways and aquatic life. Delicate ecosystems can be destroyed, and species threatened.

The main difference between this and soap is that laundry soaps use biodegradable and natural ingredients. They won’t cause nearly as much damage to the environment.

Detergent vs laundry soap: Who wins?

You’re likely wondering what’s better between laundry soaps and detergents. I really can’t answer that qu