For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
The expiration date on the lens package indicates the last month and year that the container should be considered free from contamination and the lenses inside safe to wear. It is not unusual for the expiration date of a soft contact lens to be four years from the date the lens was manufactured and packaged.