Age of children
The current age of your children. The difference between their current age the age they start college is the number of years you have to save.

Age to start education
The age your child will begin college. The default is 18, but this can be any age up to 25.

Annual tuition
The current estimated cost of one year of tuition and books. This amount should be per child and be specific to the school they may be interested in attending. The average published costs of college for the 2014-15 school year (including tuition, room and board, books, supplies, transportation and other personal expenses) as reported by the College Board.

For the purposes of this calculator all expenses are assumed to be due at the end of the year.

Room and board
The current estimated cost of one-year room and board. Like tuition and books, this amount should be per child and specific to the school they may be interested in attending. For the purposes of this calculator, all expenses are assumed to be due at the end of the year.

Education cost inflation
This is the percentage that you expect educational costs to increase per year. Data provided by the 'Trends in College Pricing 2014' from the College Board put tuition, room and board increases at an average of 2.47% per year for the last ten years.

Current amount
The total amount you currently have saved for your children's education.

Monthly contributions
The dollar amount you plan to save per month toward your children's education. All amounts are assumed to be added to your account at the beginning of the month.

Rate of return
This is the annually compounded rate of return you expect from your investments. This will also be the rate used if you end up with a negative balance and need to borrow money to meet your goal. The actual rate of return is largely dependent on the types of investments you select.