The diameter of the umbrella dome when unfolded. The larger the diameter of the dome, the more reliably it will protect you from rain and the easier it will be to place one more person under the umbrella. On the other hand, a wide umbrella can be uncomfortable in tight spaces — for example, in the flow of pedestrians on a busy street — and when folded it will take up more space. Therefore, it does not always make sense to choose the largest of the available options.
The minimum diameter for an "adult" umbrella (see "Destination") is considered to be about 80 cm. Most models are in the range of 90 – 110 cm — this provides a good degree of protection with ease of movement. And in
the largest modern products, the diameter of the dome can reach 150 cm.
Total weight of the umbrella.
All other things being equal,
lighter umbrellas are more convenient to carry (both in the open and closed positions). On the other hand, such products are less reliable and/or more expensive than relatively heavy models of similar design and size. We also note that in some cases, significant weight can be an advantage. For example, in a strong wind, a massive umbrella does not “tear from your hands” as much, and when released, it does not fly as far as a lighter one.