Castile Soap vs Regular Soap: What Is the Difference?

Castile soap has a reputation as the simple, natural choice. Here is how it actually differs from what most people use.

What castile soap is

Castile soap is soap made from vegetable oils, traditionally olive oil, with no animal fats. Today the term also covers bars and liquids made with coconut and other plant oils. More in what is castile soap.

What "regular soap" usually means

• Commercial true soaps often use palm, coconut or tallow, plus fragrance and additives.
• Beauty bars and body washes are often synthetic detergent products rather than soap.

Side-by-side

• Ingredients: castile is usually a short list of plant oils; regular products vary widely.
• Animal fats: castile has none; some commercial bars use tallow.
• Feel: olive-rich castile is mild with a low lather; coconut-based castile lathers more.
• pH: castile is true soap, so it is alkaline. Syndet bars can be closer to skin pH.
• Uses: liquid castile is famous for doubling as a household cleaner.

Is castile soap better?

Not automatically. It suits people who want simple, plant-based soap. People with very dry or sensitive skin may prefer an unscented castile bar or a gentle syndet. See soap pH explained.

Price and value

Castile soap often costs more per bar than supermarket soap but less than many boutique handmade bars. Liquid castile is concentrated, so a bottle can go a long way once diluted for cleaning. If you use one product for body, hands and household cleaning, it can work out good value.

Who should choose which

• Want a short, plant-based ingredient list: castile.
• Want one product for body and household cleaning: liquid castile.
• Very dry, sensitive or eczema-prone skin: a fragrance-free syndet bar may feel gentler.
• Love big lather and a strong scent: many regular soaps and body washes deliver this.
• Vegan: castile is plant-based by definition; regular soap may contain tallow (sodium tallowate).

Spotting tallow in regular soap

Look for sodium tallowate on the label. It is saponified beef fat. It makes a hard, mild bar and has been used in soap for centuries, but it is not suitable if you avoid animal products.

Dove, Ivory and other common brands

Dove describes its Beauty Bar as a mild cleansing bar, not soap; it is a syndet-based product. Some other well-known bars are true soaps made with tallow or palm and coconut. Castile soap differs mainly in using only plant oils and, often, having fewer additives. Neither type is automatically better; it depends on your skin and priorities.

Want to check what your current soap really is? Our free soap label decoder tells you in seconds whether a label is true soap, a syndet or a mix.

Getting the most from castile

Liquid castile is concentrated, so dilute it. Our guide to how to use castile soap lists amounts for common uses.