Margill easily does your regular amortization but also what no other interest calculation software can do:

• Allows any payment period with any compounding period
• Allows payment periods for any number of days (Payments every 5, 10, 12, 27, 100… days? No problem)
• Allows the use of a fixed interest rate that may change over time, or an interest table with an unlimited number of past or future interest rates
• Allows to compute a loan with any reimbursement method or combination thereof
  
  
  • Interest only for x months or years, then a normal reimbursement
  • Fixed principal then normal reimbursement
  • Multiple combinations
    
    
• Allows the computation of APR (nominal and effective APR) for any type of loan whether regular or irregular, fixed interest rate or variable interest rate
• Allows completely irregular payment schedules
  
  
  • Missed payments
  • Late payments
  • Extra payments
  • Lesser or greater payments
  • Lump sums
  • Additional principal
  • Late fees
    
    
• Allows any irregular schedule followed with a recomputation of regular payments to give a balance = 0.00 or any other amount
• Allows the computation of the fixed interest rate (or return) of a totally irregular loan or investment
• Optional Simple interest used for "short" periods (payment period less than one full normal period)
• Last interest charge adjusted to yield precisely equal payments
• Includes the four (4) most commonly used Day counts (ISO nomenclature)
  
  
  • Actual/Actual (also known as Actual/365
  • Actual/365 (Fixed)
  • 30/360
  • Actual/360
    
    
• Allows the use of 52, 52.143 or 52.286 (leap year) weeks in a year
• Year base for simple interest based on the civil year or loan anniversary date
• Detailed printed reports that include quarterly and annual subtotals
• Detailed printed reports that include fiscal year-end totals (a feature particulary useful for accountants)