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Step 1
Find out your current yearly mortgage interest rate. Even if you have an adjustable mortgage rate, you should know your mortgage rate at any given moment.
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Step 2
Find out how much principal you owe. This is the total amount of debt you need to pay off.
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Step 3
The basic formula for a monthly mortgage interest calculation is to multiply your principal amount by the yearly interest rate divided by 12. For example, if you owe $300,000 and you have a yearly interest rate of 5%, then your interest for this month is 300000* 0.05/12, or $1250.
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Step 4
Each month you should check your mortgage statement to see that the principal and interest amounts are correct because some mortgage servicers can be very dishonest.








