It's how most transcripts translate a year of study into the credits colleges expect to see. For homeschoolers it's a practical yardstick: log the hours and work in a subject, and once you're in the right range you can record a credit with confidence. Romeschool's transcript tools total hours and work as you go.
Carnegie Unit
Doug Berry
Homeschool dad & founder of Romeschool
A standard measure of high-school credit — roughly 120 hours of work in a subject equals one credit.