How many letters does a chassis number have?

A chassis number, also known as a Vehicle Identification Number (VIN), typically consists of 17 characters. These characters include both letters and numbers, though specific letters are often excluded to avoid confusion with similar-looking numbers (e.g., I, O, and Q). The 17-character format was standardized by the International Organization for Standardization (ISO) in 1981 to ensure uniqueness and consistency across vehicles.