Because it can be apparently used for everything, except to cure cancer.
Dr. Bronners is a hippie freaky deaky soap that can be used from everything as a pest spray and household cleaner to shampoo and mouth wash. It's a travel favorite among some circles because of its sheer versatility, and is biodegradable making it perfect for camping. (I don't really camp.)
And a little bit goes a long way. Like a looong way. And although there are no scientific studies on how long it would actually last, our (completely unscientific) trials indicate about 18 instances per ounce.
How we got our results
To get an idea how long a travel-sized bottle of Dr. Bronner's would last, we took a bottle with us to New York and Mexico City, accounting for how often it would be used on a regular basis. (It was used once daily in NYC but thrice daily in Mexico City1).
On our first real-world run, we used it once daily, going through two ounces of Dr. Bronner's in a month's time (or 15 uses per ounce). Obviously, the more we used it for other things, the faster we would go through it. Once we kicked that number up to three times per day, an ounce would only last about a week (or 21 uses per ounce).
There's obviously some variable about how much product we were using, but on average, Dr. Bronner generally lasted 18 uses per ounce. In the travel-sized, 2-ounce version they sell in stores, this means that would last 36 uses. This was the baseline for our results and the calculator.
Ultimately, how long Dr. Bronner's would last you depending on (1) the bottle size and (2) how many purposes it was used for (how many regular times we used it for different things like shampooing, body washing, etc., assuming daily usage).
| Daily Usage | Bottle Size (Ounces) | ||
| 2 | 3 | 3.3 | |
|---|---|---|---|
| 1 | 36 | 54 | 59 |
| 2 | 18 | 27 | 30 |
| 3 | 12 | 18 | 20 |
| 4 | 9 | 14 | 15 |
| 5 | 7 | 11 | 12 |
| 6 | 6 | 9 | 10 |
| 7 | 5 | 8 | 8 |
| 8 | 5 | 7 | 7 |
| 9 | 4 | 6 | 7 |
| 10 | 4 | 5 | 6 |
