BNF may stand for:
In computer science:
- Backus–Naur Form, a formal grammar for expressing context-free grammars
- Beta normal form, a potential state for a term in Lambda calculus
In science:
- Biological nitrogen fixation, a process that converts nitrogen in the atmosphere to ammonia
- British National Formulary, the standard drug reference manual
- British National Formulary for Children
- British Nutrition Foundation, a charity
In politics:
- Balawaristan National Front
- Baloch National Front, a Baloch nationalist coalition in Pakistan
- Belarusian (National) People's Front "Revival", better known as the BPF, a political party created in Belarus during the perestroika times (BNF is from the Latin translitteration of the Belarusian Беларускі Народны Фронт "Адраджэньне" (БНФ):Biełaruski Narodny Front "Adradžeńnie")
- Botswana National Front
- British National Front, a far-right political party in the United Kingdom
Other uses:
- Bibliothèque nationale de France (BnF), the French national library in Paris
- Big Name Fan, a member of a fandom who is particularly well-known
- British Nuclear Fuels (properly "BNFL")