The flammability rating or classification of a blanket is usually determined by performing relevant flammability tests. Here are some common flammability testing standards and classification systems:

1. American Standard: The U.S. Consumer Product Safety Commission (CPSC) has issued flammability testing requirements for flammable fabrics, including blankets. According to CPSC standards, blankets may be classified into the following three classes: Class 1, Class 2 and Class 3. Class 1 represents the best flammability performance, while Class 3 represents the lowest flammability performance.

1. European standard: The European standard system adopts the EN ISO 12952 standard to evaluate the flammability of home textiles. According to this standard, blankets may be divided into several categories, such as C1, C2, C3, etc. These categories represent different burn performance levels of the blanket, with C1 representing the best flammability performance.

1. Other national standards: Other countries and regions may have their own flammability testing standards and classification systems, such as the British BS 5852 standard. These standards generally require a burning test to evaluate the blanket's burning speed, flame spread and other indicators when burning, and classify it according to the test results.

It should be noted that specific flammability classes or classifications may vary by country, region and application. Therefore, understanding the flammability testing standards and classification systems for a particular region or industry is an important step in ensuring that blankets meet the appropriate requirements.