住宅ローン償還計算ツール
The detailed guide below is currently available in English.
How extra payments shorten a mortgage
Each month the loan charges interest on the remaining balance; everything above that interest reduces principal. Adding even $100 a month removes principal earlier, so every later month charges interest on a smaller number — the effect compounds and the schedule ends years ahead. The table shows the accelerated schedule; the summary rows quantify exactly how many payments and how much interest you avoid compared with paying only the standard amount.
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Should I make extra payments or invest instead?
Extra mortgage payments are a guaranteed, tax-free return equal to your loan rate. If your investments can reliably beat that rate after tax, investing may win — but the mortgage savings are certain while returns are not.
Do lenders restrict extra payments?
Most U.S. home loans allow unlimited prepayment, but some have prepayment penalties in the first years, and UK/Canadian products often cap penalty-free overpayments. Check your loan terms; this calculator assumes the extra amount is always applied to principal.