In the past, I've used a tiny 0.85 oz tube of toothpaste. They are expensive for the amount of toothpaste that you get. After using it up, I've added toothpaste to the small tube by pressing a big tube of toothpaste. It requires precision to line up the two tubes. You must press hard to avoid a mess.

Thankfully, I've discovered that Crest makes a fairly big 2.9 oz tube of toothpaste. It complies with the TSA 3-1-1 rule that limits permissible gels and liquids to 3.4 oz/100 ml size or smaller. It is moderately priced. I've seen it sold for between $1.00 and $1.75 (Walmart, Dollar General). That favorably compares in price to the 6.4 oz size often used at home. Furthermore, it lasts an entire trip and then the next trip and more. The tiny 0.85 oz tube does not reliably last a week unless it is completely full. This is partly because there will always be some toothpaste inside, possibly 0.15 oz (if so leaving 0.7 oz of toothpaste to use versus 2.75 oz with a 2.9 oz. tube).

This is great! So happy!