1. Usage frequency: If used only once a day in the morning and with a moderate amount applied each time (covering approximately the entire face and neck), then 35 milliliters of sunscreen can be used for about a month.
2. Application area: If the application area is limited to the face and does not include other exposed areas such as the neck and arms, the usage time will be relatively longer. On the contrary, if the application area is large, the usage time will be correspondingly shortened.
3. Outdoor activity time: If you spend a long time outdoors, you may need to reapply sunscreen more frequently, which will also shorten its usage time. When there is less indoor work or activity, the usage time is relatively longer.