How long will a travel-size tube of toothpaste last on a long-distance hike or any other circumstance? We analyzed four different travel-sized tubes to find out. We weighed various quantities of toothpaste and then photographed it. So you can see what different volumes of toothpaste looks like.
The American Dental Association recommends a pea-size amount of toothpaste. This is about 0.25 grams (0.0088 ounces) of toothpaste. From this data we were able to calculate the theoretical number of uses in each tube of toothpaste.

Four common travel-size toothpaste tubes.

I used a calibrated balance to accurately make measurements. Here you can see 0.515 grams of toothpaste. This is a larger volume than recommended by the American Dental Association.
Weighing Toothpaste

Large Application
This large application of 0.80 grams is more than three times the application recommended by the American Dental Association. This overuse will deplete a travel-size (24 grams) tube in about two weeks when brushing twice a day.

Recommended Application
This pea-size application of 0.25 grams of toothpaste is the amount recommended by the American Dental Association. This is the optimal amount to use and will deplete a travel-size (24 grams) tube of toothpaste in about 48 days, or almost 7 weeks, when brushing twice a day.

Medium Application
This medium application of 0.52 grams is more than two times the application recommended by the American Dental Association. This overuse will deplete a travel-size (24 gram) tube in about three weeks. This is when brushing twice a day.

Tiny Application
This tiny application of 0.08 grams should not be used because it is less than the American Dental Association recommended amount.
How much toothpaste should I use?

Conclusion
Travel-size tubes carry about 1 ounce or 29 grams. Any one of the travel sized tubes should last for about 48 days. This is if you use the recommended pea-sized amount (0.25 grams) twice a day. You can easily determine the number of applications for your tube of toothpaste. Just take the content weight in grams and divide by 0.25.
Money-saving Refill Tip
You can save money by refilling your travel-sized tube from a larger tube.

Place the empty travel tube firmly against the larger tube. Gently squeeze the larger tube to transfer the toothpaste.