Ever get ready for a long trip and wonder whether that travel-sized bottle of shampoo is going to cut it? Should you throw in another bottle just in case?
Sometimes, if I have a particularly long trip coming up, I'll throw in more one bottle of the same type, i.e. two shampoo bottles, just to make sure my bases are covered. And if I don't have the space for the extra bottle, I still save more money from not checking in ($25 for a domestic bag) and buying an extra travel-sized bottle (usually no more than $1-3) later on the road. You still come out ahead in the end.
But how the hell do you know how long a travel-sized product will last? TripAdvisor poster TABofotd claims that a travel-sized shampoo will last 3 weeks, conditioner will last 6 weeks, hair spray and hair gel will last a month. For a dude, that might work. As a girl, I completely disagree. So in the end, I decided to test it all crazy-like to see how long I could go on a full, TSA-approved bottle of shampoo. Turns out most people should gauge around 2 weeks, maybe more, depending on a couple of factors. Lazy readers should just skip to the chart below directly.
First, we need to be clear about how big a travel-sized bottle is actually is. The amount you're technically allowed to carry on is 100 mL or 3.33 ounces. Most of the world knows it's just easier to default to 100 but if you're from the States, most people generally round down to a flat 3 ounces because that's a heck of a lot easier to remember. However, if you're really want to pack in every single drop of liquid that you can, you can get away with 3.4 ounces.
There's two factors you'll have to consider before figuring out how much that teeny little bottle will last you, though. The first thing to keep in mind is that note every "travel-sized" product is 3 or 3.4 ounces; all it means when the manufacturer slaps "travel-size" on there is the amount of liquid in there is less than the TSA limit. I've had plenty of travel-sized products with about only one ounce in there so these days I scrutinize that number on the bottom a little bit more in the store. One ounce will barely get me through three days or four days!
The second thing to remember is that your own personal usage will differ from everyone else because everyone's got their own showering habits. For instance, I have long, thick Asian hair and sometimes I've really got to use more than the average person just to get a good lather going on. On top of that, I go through conditioner much faster than I use shampoo to comb out all the tangles. Some people also condition only occasionally; I'm forced to condition every day.
If I use about a tablespoon of product -- a generous amount in my opinion -- each time, that should last me about 6 uses in a 3-ounce bottle (6.8 uses in a 3.4-ounce bottle). On the realistic end of the spectrum, if you're conserving how much you're using each time by half, you could get away with 12 uses or more (13.5 uses in a 3.4-ounce bottle). This means you're averaging about 1.5 teaspoons or less each time. Assuming you shower once a day, at the bare minimum, and depending on your use, a travel-sized bottle should last you anywhere from a week to two weeks. Guys should have it much easier.
To make it easy, I took two of the most common sizes and made a couple of calculations to get some estimates on how long some shampoo (or even body lotion) would last me:
To see how this held up in real life, I then took a 3-ounce bottle of shampoo with me on the road... and I kept counting until I ran out of product. Averaging about a teaspoon (I needed far less for this particular brand), which is far less than what I usually use, it lasted me 22 uses or 22 nights, or roughly three weeks. This means I got about four more uses out of it than I thought I would. At the same time, I was trying to squeeze every little bit out at the end.
The above chart is only a guideline but there's room for deviation there. Says my unscientific test. Your mileage may vary depending on how much hair you have.
This post originally appeared on Map Happy.