The same €300,000 mortgage over 25, 30 and 35 years
Borrow €300,000 at 4% and the mortgage term alone decides how the numbers land. Over 25 years the monthly repayment is €1,583.51 and the total interest is €175,053. Stretch the same loan to 30 years and the monthly repayment falls to €1,432.25, but total interest climbs to €215,609. Stretch it further to 35 years and the monthly repayment falls again, to €1,328.32, while total interest rises to €257,896. Same amount borrowed, same rate — the years are doing all of that.
The table
| Term | Monthly repayment | Total interest | Total repaid |
|---|---|---|---|
| 25 years | €1,583.51 | €175,053 | €475,053 |
| 30 years | €1,432.25 | €215,609 | €515,609 |
| 35 years | €1,328.32 | €257,896 | €557,896 |
Reading it
Each step of five extra years buys a cheaper month and a costlier loan. Going from 25 to 30 years knocks €151.26 off the monthly repayment but adds €40,556 to the total interest bill. Going from 30 to 35 years saves a further €103.93 a month and adds another €42,287 in interest. By 35 years, the interest alone — €257,896 — is closing in on the size of a small mortgage in itself, on top of the €300,000 actually borrowed.
Why the term does this
A mortgage charges interest on whatever balance is still outstanding, every month, for as long as that balance survives. A longer term means slower repayment of the capital, which means the balance stays higher for longer, which means more months of interest charged on more euros. The monthly repayment looks kinder because it’s spread over more payments, but the loan is doing more work for the bank in the meantime, not less.
The escape hatch
A long term paired with voluntary overpayments behaves like a short term with a safety net: you get the lower contractual monthly repayment as your floor, but you can pay down the balance faster whenever you have room, cutting the interest bill without losing the flexibility — the overpayments example works through exactly how much that can save.
Try your own numbers
The mortgage calculator will run these same figures for your own amount, rate and set of terms, so you can see exactly what each extra year costs.
Assumptions: €300,000 borrowed at a fixed 4% interest rate, repaid in equal monthly instalments (a standard repayment mortgage), with no overpayments, fees or rate changes over the life of the loan.