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).
Don't forget about the cost of contact lens solutions to clean and disinfect your lenses. If you wear contacts on a daily wear basis and clean and disinfect them after each use, expect your annual cost for contact lens care solutions to be roughly $150 to $200.