When buying a compact travel umbrella, the size of its canopy is one of the most important factors. You want an umbrella that is big enough to provide good protection from rain but small enough to fit in your bag or backpack. In general, you will want to go with a compact umbrella that is no more than 10 inches long when closed.
Another important factor to consider is how lightweight and durable a particular umbrella is. Typically, the best travel umbrellas will be made from fiberglass and fiber-reinforced plastic, which makes them lightweight and resistant to wind and other weather conditions. You may also want to look for a travel umbrella that has been treated with a waterproof coating, which is even more durable.