Category 3

Category 3 or Category III can refer to:
 * Category 3 cable, a specification for data cabling
 * British firework classification
 * Category 3 tropical cyclone, on any of the tropical cyclone scales
 * Category 3 pandemic, on the Pandemic Severity Index, an American influenza pandemic with a case-fatality ratio between 0.5% and 1%
 * Category 3 winter storm, on the Northeast Snowfall Impact Scale and the Regional Snowfall Index
 * Any of several winter storms listed at list of Northeast Snowfall Impact Scale winter storms
 * Category 03 non-silicate mineral - Halides
 * Category III, a rating in the Hong Kong motion picture rating system
 * Category III, a capability level of aircraft instrument landing systems
 * Category III New Testament manuscripts - Eclectic
 * Category III measurement - performed in the building installation
 * Category III protected area (IUCN) - natural monument