预防成本是有关企图预防不良产品或服务发生的成本，包括计划与管理系统、人员训练、品质管制过程，以及对设计和生产两阶段的注意以减少不良品发生的机率所产生的种种成本。

"质量成本" 模型主要有4方面的成本：

1. 预防成本：用于防止残次品产生的成本，例如：更好的培训，可靠性研究等等，主要目的在从生产过程中减少残次品的产生。

2. 评估成本：用于监管，评估产品是否符合标准的成本，例如：产品抽样、测试，设备维护等等。

3. 内部故障成本：指残次品（不符合生产/客户 要求的产品或者服务）在送达客户之前被发现所产生的成本，例如：报废品（无法再加工的残次品），再加工，以及所有相关的损失（比如生产次品花费的时间成本）

In process improvement efforts, quality costs or cost of quality is a means to quantify the total cost of quality-related efforts and deficiencies. It was first described by Armand V. Feigenbaum in a 1956 Harvard Business Review article.

Prior to its introduction, the general perception was that higher quality requires higher costs, either by buying better materials or machines or by hiring more labor. Furthermore, while cost accounting had evolved to categorize financial transactions into revenues, expenses, and changes in shareholder equity, it had not attempted to categorize costs relevant to quality, which is especially important given that most people involved in manufacturing never set hands on the product. By classifying quality-related entries from a company's general ledger, management and quality practitioners can evaluate investments in quality based on cost improvement and profit enhancement.