Total Interest Paid Calculator

Last updated July 2, 2026

Total interest paid over the life of a loan is the number that most loan documents de-emphasize and most borrowers never calculate before signing. It's required to appear in federal Truth in Lending Act disclosures, but it's buried in a block of standardized text that few borrowers read carefully. For a 30-year mortgage at 7 percent on a $350,000 loan, the total interest paid over the full term is approximately $488,000 — slightly more than the original principal borrowed. The home that costs $350,000 actually costs $838,000 when financed at current rates over the standard term. That figure doesn't make the purchase wrong, but it should inform the analysis of whether a shorter term, a larger down payment, or aggressive prepayment is worth the financial sacrifice involved.

The total interest figure is most useful as a decision variable, not a discouragement tool. A 15-year mortgage on the same $350,000 at 6 percent generates $162,000 in total interest — $326,000 less than the 30-year scenario, though the monthly payment is $977 higher. Whether that trade-off is worthwhile depends on what else the $977 monthly difference could produce — if it would go into retirement accounts earning 8 to 10 percent historically, the comparison between mortgage payoff and investment returns is relevant and nuanced. If it would simply be absorbed into lifestyle spending, the 15-year term is almost certainly the better choice.

Always calculate total interest paid before signing any major loan. For mortgages especially, compare the 30-year and 15-year total interest figures side by side. The dollar difference often exceeds $200,000 and represents the true long-term cost of choosing a longer term for a lower monthly payment — a trade-off worth making deliberately, not by default.