A typical school bus ranges in length from about 20 feet to 45 feet. Short buses are usually between 20 to 25 feet long, medium-sized buses range from 25 to 35 feet, and full-length school buses are generally 35 to 45 feet long. The most common full-size school bus is about 35 feet long and can seat around 72 passengers, while the largest can reach up to 45 feet, sometimes carrying up to 90 passengers.