I am trying to figure out if I can afford a deal. I have put these numbers through a few different calculators available on-line, but want to be sure I am figuring this correctly. I have a private investor (my friend, not experienced) who would like to give me a loan for an eventual flip (we are holding it for one year first which has nothing to do with the flip itself, but a family matter), and we agreed that I would pay her interest only on her principal for that year. After that year, we're going to convert it to a different kind of profit sharing deal for the flip. But in that year, how would the interest only standardly be calculated. I amortized it over 30 years with the interest rate we agreed upon, then chose one year as interest-only. Does this make sense? Does it work like a normally amortized loan, as in would I be paying more interest up front in that first year? I can barely justify the payment the way I'm figuring it, and am hoping perhaps that isn't the way the math should be done. I used a different calculator and it gave me a lower figure, but have no idea why. If it helps, the principal balance will be $80,000 with an interest only rate of 6% for one year (or less, depending on the family matter). I hope I am being clear in my question above. Thanks for your help!