- Category I: 23-24 weeks (575-600 hours) Languages closely related to English
- Category II: 30 weeks (750 hours) Languages similar to English
- Category III: 36 weeks (900 hours) Languages with linguistic and/or cultural differences from English
- Category IV: 44 weeks (1100 hours) Languages with significant linguistic and/or cultural differences from English
- Category V: 88 weeks (2200 hours) Languages which are exceptionally difficult for native English speakers
* Usually more difficult than other languages in the same category.