text: Web EndMemo
  
   Annual Percentage Rate (APR) Calculator
  Loan Amount:
  Loan Fees:
  Interest Rate (%):
  Pay Term (Month):
  Closing Fees:
  
  Monthly Payment:
  Total Payment:
  Total Interest Payed:
  Direct-ratio APR (%):
  Constant-ratio APR (%):
  N-ratio APR (%):
  
  Annual Percentage Rate (APR) is the equivalent interest rate of a loan including all loan fees and interests payed. The monthly payment is calculated using following formula:
  
  Where:
  P: Monthly payment
  C: Initial loan amount
  E: All loan fees
  r: Interest rate (%)
  N: Pay terms
  
  The total amount payed (T) is:
  T = P * N + F
  
  The total interest payed (I) is:
  I = P * N - C - E
  
  The direct-ratio APR formula is:
  a = 6M * B/(3C(N+1) + B(N+1))
  
  The constant-ratio formula is:
  a = 2M * B /(C(N+1))
  
  The N-ratio formula is:
  a = M(95N + 9) * B/(12N(N+1)(4C + B))
  
  Where:
  a: APR
  M: Number of payments per year
  B: Total finance charges
  F: Closing Fees
  
  APR calculation Example:
  A \$300,000 loan with \$4,000 other fees and an annual interest rate 5%, the payback term is 10 years.
  The monthly payment = (300000 + 4000) * 0.05 * (1 + 0.05)120 / ((1 + 0.05)120 - 1) = 3224.39
  The total payment = 3224.39 * 120 = 386927
  The total interest = 386927 - 300000 = 86927
  The Direct-ratio APR is 5.241%.
  The Constant-ratio APR is 5.747%.
  The N-ratio APR is 5.307%.
  
  Note: The most frequently used method by the lender is the actuarial method, while the formula for which is complicated due to the loan structure.