How many years of college does a biometrian have to take?

There's no single answer to how many years of college a biometrician needs. The minimum requirement is usually a bachelor's degree (4 years), but many positions, especially those involving more advanced research or leadership, prefer or require a master's degree (6 years total including undergraduate) or even a PhD (8+ years total including undergraduate). The specific degree might be in biostatistics, statistics, mathematics, or a related field with strong quantitative components.