In the quarter system, students receive less than a full student hour, so students must take more classes to gain the equivalent class time of the semester system. When transferring credit, students' credit hours are adjusted based upon the systems used between the two institutions.
https://en.wikipedia.org/wiki/Carnegie_Unit_and_Student_Hour
1 The Academic Calendar must have a minimum of 750 minutes of instruction per credit hour. 2  The standard meeting times for courses are a 50-minute, Monday-Wednesday-Friday schedule and a 75-minute, Tuesday-Thursday schedule. 3  For the standard 3-credit hour course, 2,430 minutes of instruction are required.
http://registrar.unc.edu/academic-services/policies-procedures/university-policy-memorandums/upm-29-definition-of-a-credit-hour/
Per its original definition, the Carnegie Unit is 120 hours of class or contact time with an instructor over the course of a year at the secondary (American high school) level. Strictly speaking, this breaks down into a single one-hour meeting, on each of five days per week for a total of 24 weeks per year.
https://en.wikipedia.org/wiki/Carnegie_Unit_and_Student_Hour
1 One credit is equivalent to 50 minutes (at a minimum) of class time (direct instruction) and a minimum of two hours of out of class student work per week. 2  Three-credit course will typically meet 150 minutes per week for 15 weeks (37.50 hours, direct faculty instruction).
http://www.loyola.edu/department/records/about/credit-hours
1 For the standard 3-credit hour course, 2,430 minutes of instruction are required. 2  The calendar is planned with a minimum of 42 Monday-Wednesday-Friday meeting days and 28 Tuesday-Thursday meeting days. 3  The policy allows a mandatory examination period to be counted in the minutes of instruction.
http://registrar.unc.edu/academic-services/policies-procedures/university-policy-memorandums/upm-29-definition-of-a-credit-hour/
1 The standard meeting times for courses are a 50-minute, Monday-Wednesday-Friday schedule and a 75-minute, Tuesday-Thursday schedule. 2  For the standard 3-credit hour course, 2,430 minutes of instruction are required.
http://registrar.unc.edu/academic-services/policies-procedures/university-policy-memorandums/upm-29-definition-of-a-credit-hour/
1 The University Registrar chairs the University Calendar Committee that prepares and recommends the annual Academic Calendar for approval by the Chancellor no less than 18 months in advance of the planned academic year. 2  The Academic Calendar must have a minimum of 750 minutes of instruction per credit hour.
http://registrar.unc.edu/academic-services/policies-procedures/university-policy-memorandums/upm-29-definition-of-a-credit-hour/
A semester (one-half of a full year) earns 1/2 a Carnegie Unit. The Student Hour is approximately 12 hours of class or contact time, approximately 1/10 of the Carnegie Unit (as explained below). As it is used today, a Student Hour is the equivalent of one hour (50 minutes) of lecture time for a single student per week over the course of a semester, usually 14 to 16 weeks.
https://en.wikipedia.org/wiki/Carnegie_Unit_and_Student_Hour
ABHES Definition Semester-minimum of 15 weeks in length. One semester credit is equal to: • one hour of lecture per week for a semester or the equivalent number of hours.• two hours of lab per week for a semester or the equivalent number of hours.
http://www.abhes.org/assets/uploads/files/2011-02-224d6410418ac2dCalculating_Credit_Hours_in_Online_&_Blended_Learning.pdf
• three hours of externship/clinical per week for a semester or the equivalent number of hours. Quarter-minimum of 10 weeks in length. One-quarter credit is equal to: • one hour of lecture per week for a quarter or the equivalent number of hours. • two hours of lab per week for a quarter or the equivalent number of hours. • three hours of externship/clinical per week for a quarter or the equivalent number of hours.
http://www.abhes.org/assets/uploads/files/2011-02-224d6410418ac2dCalculating_Credit_Hours_in_Online_&_Blended_Learning.pdf
hours of instruction per credit hour
There are 2,430 minutes of instruction per credit hour.