How to get periodic interest rate for Flat Interest Rate?

I've a project which need to create a html based calculator for Effective Interest Rate.

I'm stuck at Periodic Interest Rate part. Anyone know how to calculate the periodic interest rate.

The image above is the formula to calculate size of each payment. The i is the periodic interest rate. Anyone know how to convert the formula?

Thank you

Tue Jul 05, 2011 7:06 am

oldguy Senior Member

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There isn't a classic solution for 'i' in your equation - it can only be determined from a mathematical series. In the case of a mortgage, you would write the 360 equations for each of the 360 months, then add the series. It could take a few days - (that's why we invented computers, LOL)