Table of Contents### Calculating Cumulative Principal and Interest

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Knowing how much principal and interest you pay each period is useful, but it's usually more often handy to know how much principal or interest you've paid in total up to a given period. For example, if you sign up for a mortgage with a five-year term, how much principal will you have paid off by the end of the term? Similarly, a business might need to know the total interest payments a loan requires in the first year so that it can factor the result into its expense budgeting.

You could solve these kinds of problems by building a model that uses the `PPMT()` and `IPMT()` functions over the time frame you're dealing with and then summing the results. However, Excel's Analysis ToolPak has two functions that offer a more direct route: