Consideration in contract law is the value or benefit given by each party in exchange for the other party’s value or benefit—such as money in exchange for products or services, or mutual promises exchanged. Consideration is often referred to as the bargained-for exchange in which one consideration is exchanged for another consideration.

A mere promise to do or refrain from doing something that lacks consideration in the form of a value or benefit provided by the other party (a return promise) is not a contract and is generally not enforceable. One exception to this rule may be if one party promises to do or refrain from doing something, and the second party relies on that promise to its detriment (by spending money, for example), the detrimental reliance may create an enforceable contract.

And if the consideration for a contract is so insubstantial that it is worthless, the contract is said to be illusory and is not enforceable.

In Hawaii, as in other states, consideration is a fundamental component of a valid contract. Consideration refers to something of value that is exchanged between parties when entering into a contract. It can be a payment, service, or a promise to perform or refrain from a certain action. The consideration must be something that the parties have bargained for and is the reason for entering into the contract. Without consideration, a promise or agreement is typically not enforceable as a contract. However, Hawaii recognizes the doctrine of promissory estoppel, which means that if one party makes a promise and the other party relies on that promise to their detriment, the promise may be enforceable even without consideration. This is to prevent injustice due to the relying party's reasonable assumption that the promise would be fulfilled. Additionally, if the consideration is deemed to be 'illusory'—meaning it is so insignificant that it cannot be considered a true exchange of value—the contract may be considered unenforceable in Hawaii. Attorneys in Hawaii would assess the sufficiency of consideration on a case-by-case basis to determine the enforceability of a contract.