Is castile soap the same as olive oil soap?

Traditionally, yes. Castile soap meant a hard soap made from olive oil, in the style of the Castile region of Spain. Today the name is not legally protected, and many products sold as castile are made mainly from coconut and palm oil. A soap is an olive oil soap if sodium olivate, or olive oil saponified with lye, comes first on its ingredient list.

Is Dr. Bronner's castile soap made from olive oil?

It contains olive oil, but olive oil is not the main oil. On the company's own ingredient page, the liquid soap lists water, coconut oil, potassium hydroxide and palm oil before olive oil, and the company says it raised the coconut share in 2024. It is a true soap made from plant oils, which is what castile now often means, rather than an olive oil soap.

What is the difference between liquid and bar castile soap?

The alkali. Liquid castile is made with potassium hydroxide, which gives potassium soaps that stay liquid in water; bar castile is made with sodium hydroxide, which gives a solid bar. Because olive oil alone makes a thin, low-foaming liquid soap, most liquid castile products lean on coconut oil. A traditional bar lists sodium olivate first.

Why does pure olive oil soap feel slimy or lather so little?

Olive oil is mostly oleic acid, which makes a mild but soft soap with a small, creamy lather rather than big bubbles. A fresh bar can also feel slippery. Long curing helps: in a 2003 Grasas y Aceites study, castile bars stored for six months became firmer, lathered more and wore down more slowly. Letting the bar dry between uses keeps it firm.

Is castile soap good for your hair?

It can leave hair dull and tangled, especially in hard water. True soap is alkaline, while the scalp sits around pH 5.5, and a 2014 review in the International Journal of Trichology notes that soap residue forms calcium salts that build up on the hair. If you try a soap on hair, use little, rinse thoroughly and expect it to suit short or oily hair best.

Can I use castile or olive oil soap on my face?

Many people do, as a simple bar without fragrance avoids common irritants. Soap is still more alkaline than skin, so it can feel tight or drying for some. Try a new bar on a small area first and stop if it stings or causes redness. If you have eczema or another skin condition, check with a healthcare professional before changing your cleanser.

Reading the label #10

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26 October 2026 · 3 min read

Castile Soap vs Olive Oil Soap: What's the Difference?

Quick Answer

Traditionally there is none: castile soap meant hard soap made from olive oil. Today the name is unprotected, and the best-known castile, Dr. Bronner's liquid soap, lists coconut oil before olive oil. So the label tells you less than the ingredient list. If sodium olivate comes first, it is olive oil soap, whatever it is called.

Historically, castile soap and olive oil soap are the same thing: a hard soap made from olive oil, named after the Crown of Castile in Spain, where it was produced at scale. Today the word has drifted. "Castile" is not a protected or legally defined name, so it now appears on soaps built mostly on coconut and palm oil. The way to tell them apart is not the front of the pack but the ingredient list.

Where the name came from

The style traces back to the Levant. Soapmakers in Aleppo made hard soaps from olive oil and laurel oil; further west, where laurel oil was hard to get, it was dropped, leaving a bar made from olive oil alone. That white, hard soap became known in Spanish as jabón de Castilla. For centuries "castile" described a recipe, olive oil plus alkali, rather than a place you had to buy it from. Nothing in cosmetics law has since tied the word to a recipe, and that is where the confusion starts.

Today's best-known castile is mostly coconut

Open the ingredient page for Dr. Bronner's Pure-Castile liquid soap and the order is water, organic coconut oil, potassium hydroxide, organic palm oil, then organic olive oil. The company explains that coconut oil gives the soap its rich, foamy lather, and that it increased the coconut share of the formula in 2024. None of this is hidden or improper: it is a true soap made from plant oils, which is what "castile" has come to mean in much of the US market. It is simply not an olive oil soap.

Two clues tell the styles apart:

Liquid castile: made with potassium hydroxide, so it stays liquid. It is usually coconut-led, because olive oil alone gives a thin, low-foaming liquid.
Bar castile: made with sodium hydroxide. A traditional bar lists sodium olivate first.

How to read the label in ten seconds

In the EU and UK, Article 19 of the cosmetics regulation requires ingredients in descending order of weight, so the first name is the base. Sodium olivate first means saponified olive oil is the main ingredient. Sodium cocoate, potassium cocoate or sodium palmate first means coconut or palm leads, whatever the word on the front. Our longer guide, is olive oil soap sold in supermarkets, covers the synthetic detergent bars that also borrow the name.

What a true olive oil bar is like to use

Olive oil is mostly oleic acid, which makes a mild soap but a soft one, with a small, creamy lather that some people find slippery at first. That is why makers add coconut and palm. A pure olive bar needs time instead. In a 2003 study in Grasas y Aceites, castile bars stored for six months at room temperature became very firm, produced more lather and wore away more slowly in hand washing. The same study made a fine castile soap even from rancid, non-edible olive oil: for soap, the cure matters more than the grade of oil.

Milasso's handmade olive oil soap is made in Milas, Muğla, on an olive oil base by the cold process method, with no fragrance, colourant or preservative, and cures for at least six weeks. We call it olive oil soap rather than castile because that is what the ingredient list says. If you came for the oil itself, the olive oil range starts with our early harvest Memecik.

Frequently Asked Questions

Is castile soap the same as olive oil soap?: Traditionally, yes. Castile soap meant a hard soap made from olive oil, in the style of the Castile region of Spain. Today the name is not legally protected, and many products sold as castile are made mainly from coconut and palm oil. A soap is an olive oil soap if sodium olivate, or olive oil saponified with lye, comes first on its ingredient list.
Is Dr. Bronner's castile soap made from olive oil?: It contains olive oil, but olive oil is not the main oil. On the company's own ingredient page, the liquid soap lists water, coconut oil, potassium hydroxide and palm oil before olive oil, and the company says it raised the coconut share in 2024. It is a true soap made from plant oils, which is what castile now often means, rather than an olive oil soap.
What is the difference between liquid and bar castile soap?: The alkali. Liquid castile is made with potassium hydroxide, which gives potassium soaps that stay liquid in water; bar castile is made with sodium hydroxide, which gives a solid bar. Because olive oil alone makes a thin, low-foaming liquid soap, most liquid castile products lean on coconut oil. A traditional bar lists sodium olivate first.
Why does pure olive oil soap feel slimy or lather so little?: Olive oil is mostly oleic acid, which makes a mild but soft soap with a small, creamy lather rather than big bubbles. A fresh bar can also feel slippery. Long curing helps: in a 2003 Grasas y Aceites study, castile bars stored for six months became firmer, lathered more and wore down more slowly. Letting the bar dry between uses keeps it firm.
Is castile soap good for your hair?: It can leave hair dull and tangled, especially in hard water. True soap is alkaline, while the scalp sits around pH 5.5, and a 2014 review in the International Journal of Trichology notes that soap residue forms calcium salts that build up on the hair. If you try a soap on hair, use little, rinse thoroughly and expect it to suit short or oily hair best.
Can I use castile or olive oil soap on my face?: Many people do, as a simple bar without fragrance avoids common irritants. Soap is still more alkaline than skin, so it can feel tight or drying for some. Try a new bar on a small area first and stop if it stings or causes redness. If you have eczema or another skin condition, check with a healthcare professional before changing your cleanser.

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