Short Answer: It depends on how often it's used, and if it's kept dry between uses.
When used at the sink for handwashing, a bar of our handmade soap can last for around 6 weeks or more. This assumes that the bar will be placed on a soap dish that allows the water to drain away from the soap, giving the soap a chance to dry out between uses. You can read more on extending the life of your soap here.
When used in the shower, a bar of soap will typically last around 4 weeks. This assumes that the bar is exposed to water longer than at the sink, and then multiple people are using the same bar to wash head to toe.
A bar of Tooth Suds typically lasts for 3 months! A Shampoo Bar typically lasts 2-6 months (depending on how many times you wash your hair, and how long your hair is).
Compared to commercial "soaps", natural soaps are normally softer as they retain their natural glycerin (commercial soap production removes the glycerine to sell as a separate product). Our soaps are also free from artificial hardening chemicals, synthetic waxes, or free alkali.