Foam soap is a form of liquid soap which has been whipped with air to create a foam of soap bubbles. This style of soap is classically sold in specialized dispensers, often for institutional use, although foam soap can also be used at home. Foam soap comes in several different styles for various uses, and is usually readily available at drugstores and other stores which stock soaps and personal care supplies.

For manufacturers, the advantage of foam soap is that they do not need to make as much soap. They argue that foam soap is also easier to lather, encouraging people to use soap properly, and that since many people overuse soap, foam soap dispenses a more appropriate amount of soap for basic hand washing needs. Foam soap is also thinner, making the dispensers less prone to clogging.

Using foam soap also supposedly reduces waste, because the soap is easy to apply, in contrast with regular liquid soap, which may spill onto the sink or into the drain. In cost-conscious applications, foam soap can be a much better choice than conventional soap for this reason.

Like other soaps, foam soap can be formulated with antibacterial or antimicrobial properties, and it can be scented or unscented, with added ingredients to moisturize the skin and other add-ons to make the soap more appealing. Many people associate foam soap with industrial uses, like hospital restrooms, but some companies make luxury versions for home use with a focus on sweet smells and natural ingredients.

This soap requires a special dispenser, because it is thinner than regular soap. If foam soap is used to fill a normal soap dispenser, it will tend to come out in excess, making a big mess. Conversely, regular soap cannot be used to fill a foam soap dispenser, because it will clog the mechanism, although regular soap diluted with water can usually be safely used in a foam soap dispenser.

Because foam soap is often pressurized, it cannot simply be poured from a large refill jug into a dispenser. Some companies design dispensers with disposable cartridges which can be popped out and replaced when they run out of soap, while other dispensers are designed for a single use. Single use dispensers are common in environments where people are worried about bacteria and other germs, as it can be hard to keep a permanent fixture clean.