How long does a bar of soap last?

How long does a bar of soap last?

Feb 06, 2022

Barbara Marengo

Have you ever stopped mid-shower and wondered, “How long does a bar of soap last?” just before it dissolves in your hand? Now you’re faced with a classic shower dilemma: do you jump out, leaving wet tracks on the floor while making a break for the place the soaps are stored? Do you yell for help? Or do you carry on with shampoo? (which if you’re shaving, never foams quite right.)

Armed with a bit of soap know-how, it is possible to make your bar soap lather better, last longer, and save you money. Never get caught sprinting from the shower for soap again!

But first, let’s make sure we’re on the same soap dish. Today we’re talking about the lifespan of bar soap, not liquid soaps (which technically are detergents) or shower gels. Bar soap is made via the saponification process, the chemical reaction between fat and an alkali, which produces glycerol and soap.

Now here’s the tricky part about predicting how long a bar will last - soaps don’t dissolve at the same rate. What soap is made of and how you use it will determine whether a bar will last 2 weeks, 2 months, or even up to a year.

5 choices that will affect your soap’s lifespan

From a freshly opened package to a bar’s final sliver, your answers to these questions will affect how long your soap lasts:

  1. Commercial or natural?

Your soap’s ingredients will affect how long it lasts. Most commercial soap makers remove the glycerin and may use hardeners, detergent synthetic waxes, and foaming agents. You’ll have a longer-lasting soap, but you get that other stuff too. Natural soaps are softer because they retain glycerin (which softens skin) and contain natural oils that produce lather. A natural soap made of harder oils such as coconut or palm oils, palm kernel flakes or beeswax will last longer.

  1. How often do you shower or bathe?

This is the soap X-factor. It only makes sense that if you shower twice a day, your soap won’t last as long as someone who scrubs up less often. Most soap bars weigh about 99 to128 grams (3.5 to 4.5 ounces). If you shower daily, or less often, your soap can last 4 weeks or more. The average bath requires 4-5 grams (0.14-0.17 ounces) of soap - that is about 25 baths for a good-sized bar.

  1. Hot or cold?

Temperature affects your soap. Hot water dissolves soap faster than cold water. If you prefer a cooler shower, then your soap is going to last longer. However, the trade-off is that lowering the water temperature makes it harder to work up a good lather. Long life vs. more foam – that’s a tough one.

  1. Hand soaping or cleaning accessories?

Many soap purists prefer using a hand to soap up, but this approach consumes the bar faster. Cleaning accessories such as an exfoliating scrubby, loofah, or washcloth will produce the same amount of lather, but use less soap.

  1. Are you multitasking?

If you’re scrubbing, luxuriating in lather and shaving, you’ll use more soap each time than someone who only scrubs pits and bits. Got body hair? The gentle friction of body hair uses soap faster so it kind of counts as an extra shower activity.

Does a soap’s shape matter?

 Soaps can be round, oval, square, rectangular, or “unique” (like BEBA Botanica’s colourful hippos). Shape really comes down to user preference: how it looks, what feels good in the hand, and the shape that’s easiest to hold onto when the soap is wet. Some say that cutting a larger soap into smaller chunks can help it last longer because less surface area comes in contact with the water. We think you should choose the shape you like, and read on for the tips that will make a real difference to your soap’s life.

3 tips to make your bar soap last longer

There’s no need to end the relationship with your favourite bar of soap early. If you use these tips, your bar soap will last four to six weeks, or even longer.

  1. Remove soap from its packaging.

Soap goes through a curing process; giving it access to the air will encourage it to continue hardening. You may consider storing your soap with your towels, away from all sources of humidity. A linen/towel closet that’s separate from the bathroom is best. If you don’t have that luxury, then find a cool, dry place to store your soap in the bathroom.

  1. Choose high-quality ingredients.

Not only will soaps with the best ingredients cleanse, lather and moisturize, but they’ll also feel better on your skin and last longer. Many people don’t put much thought into what goes in their soap, but like other products, you get what you pay for. Find out more about the difference clean skincare makes.

 Let the bar of soap dry out between uses.

Wet soap shrinks and sitting in water reduces the quality and ability of the soap to lather. In the shower, store your soap away from water or steam. Place the soap on a raised dish with drain holes to promote air circulation. (The holes are the key – a flat soap dish won’t allow airflow.)


Enjoy a longer relationship with your soap

 A soap’s life really depends on how and how often you use it. The good news is that by keeping your soap cool and dry, choosing high-quality ingredients and letting the bar dry out between showers or baths, you can extend your soap’s life. Remember, not all soaps are created equal, so read the label and find out what you’re lathering up with. Maybe there’s a better option! Your soap should provide a luxurious experience that makes you want every bar to last as long as possible.

Find out more about the 12 ingredients you should avoid in your soap.