How many glasses of milk does a cow produce in lifetime?

Cows don't produce glasses of milk; they produce gallons. However, the amount of milk a cow produces can vary significantly depending on several factors, including the breed, size, age, health, and diet of the cow. On average, however, a dairy cow can produce several thousand gallons of milk over its lifetime. For example, Holstein cows, a common dairy breed, have been known to produce over 20,000 gallons of milk in their lifetime.