Calculable loss: There are two elements that must be at least estimable, if not formally calculable: the probability of loss, and the attendant cost. Probability of loss is generally an empirical exercise, while cost has more to do with the ability of a reasonable person in possession of a copy of the insurance policy and a proof of loss associated with a claim presented under that policy to make a reasonably definite and objective evaluation of the amount of the loss recoverable as a result of the claim.
The financial stability and strength of an insurance company should be a major consideration when buying an insurance contract. An insurance premium paid currently provides coverage for losses that might arise many years in the future. For that reason, the viability of the insurance carrier is very important. In recent years, a number of insurance companies have become insolvent, leaving their policyholders with no coverage (or coverage only from a government-backed insurance pool or other arrangement with less attractive payouts for losses). A number of independent rating agencies provide information and rate the financial viability of insurance companies.
Insurable interest – the insured typically must directly suffer from the loss. Insurable interest must exist whether property insurance or insurance on a person is involved. The concept requires that the insured have a "stake" in the loss or damage to the life or property insured. What that "stake" is will be determined by the kind of insurance involved and the nature of the property ownership or relationship between the persons. The requirement of an insurable interest is what distinguishes insurance from gambling.