Calculate Payment With a Financial Calculator

• 1). Determine the present value of your loan (the amount outstanding on your mortgage loan). For example, let's pretend your loan is for $250,000 with a 10 percent annual interest rate for 30 years. The present value is $250,000.
  
  
• 2). Calculate the per period interest rate. Using the previous example, the rate is a 10 percent annual rate, so to find the per period interest rate (in this case weekly), you need to divide 10 percent by 52 which gives you .001923.
  
  
• 3). Determine the number of periods. Using the example from Step 1, the loan is for 30 years, but since your payment will be weekly, you need to figure out the number of weeks in 30 years. So 30*52 equals 1560.
  
  
• 4). Use the present value formula to find your weekly mortgage payment: PMT = PV * ((i* ((1+i)^n) )/( ((1+i)^n) -1)) where PV is present value, PMT is payment, i is the per period interest rate and n is the number of periods.
  
  
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  Enter your specific mortgage variables into your financial calculator as follows: PMT = $250,000 * ((.001923* ((1.001923)^1560))/ (((1.001923)^1560)-1))
  
  This gives you a weekly payment of -$506.02. The number will be negative because you are paying money to the bank.
  
  

Calculate Payment Using Microsoft Excel

• 1). Determine the present value of the loan, the per period interest rate and the number of periods as above. Using the previous example these all stay the same.
  
  Present value= $250,000
  
  Per period interest rate= .001923
  
  Number of periods= 1560
  
  
• 2). Click on a cell in Microsoft Excel and type "=pmt(". This will prompt an automatic formula in Excel that shows PMT(rate, nper, pv, [fv], [type]).
  
  
• 3). Enter the characteristics of your mortgage after the parentheses in the order listed. Rate is the per period rate. Nper is the number of periods. PV is the present value. You can ignore fv and type for this calculation. Your entered formula will look like this: =PMT(.001923, 1560, 250000)
  
  
• 4). Calculate your weekly mortgage payment by pressing enter. Microsoft Excel should return -$506.02. The number is negative because it is what you pay out. This is the same amount you calculated if you used the formula above.