FL may stand for:

• Liechtenstein (country code for vehicles)
• Florida (US postal abbreviations)
• FL programming language
• flight level in aviation, a nominal altitude designation
• Freelancer (computer game), 2003, Digital Anvil, published by Microsoft
• the IATA cdoe for AirTran

fL is the abbreviation for the metric unit of volume the femtolitre (US femtoliter)

fl is used by historians as an abbreviation for "flourished," to indicate periods when civilizations were influential