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).
By law, contact lens prescriptions are valid for a minimum of one year, or the minimum required by state law, whichever is greater. Even if you buy your replacement contacts from another source, you still need to visit your eye doctor for regular eye exams and contact lens fittings.