Attach Rate

The ratio of secondary products or services sold alongside a primary product purchase.

An attach rate is a business metric that measures the proportion of secondary products, accessories, or services sold to customers who purchase a primary product. It is commonly used in technology, hardware, gaming, and automotive sectors to evaluate how effectively a company monetizes its core customer base. For example, a smartphone manufacturer might track how many buyers also purchase wireless earbuds, protective cases, or extended warranties. To calculate the attach rate, an analyst divides the total volume of secondary items sold by the total volume of primary items sold over a specific period, multiplying by 100 to express it as a percentage. In some ecosystems, the attach rate can exceed 100% if customers routinely purchase multiple different accessories or software add-ons for a single primary device. Investors pay close attention to attach rates because they are a strong indicator of ecosystem strength, pricing power, and margin expansion. Secondary products—especially software, digital subscriptions, and warranties—typically carry much higher gross margins than the primary hardware. A rising attach rate allows a company to increase its average revenue per user and lifetime value without needing to acquire new customers. A low or declining attach rate can signal that a company's ecosystem is losing its appeal, that competitors are offering better accessories, or that the primary product is becoming commoditized. However, investors should be cautious of high attach rates driven by aggressive bundling or forced tie-ins, as these practices can sometimes lead to regulatory scrutiny or customer backlash.

A gaming console manufacturer sells 2,000,000 units of its new console. During the same period, the company sells 1,600,000 units of its flagship video game designed for that console. The attach rate for the game is calculated as: (1,600,000 / 2,000,000) 100 = 80%.