Break-Even Rate Calculator
10 or 15 years fixed — which pays off? The calculator shows the follow-up rate the shorter fixation can reach at most before the longer one becomes the better deal.
At what follow-up rate does the longer fixed-rate period pay off?
The break-even rate is the highest follow-up interest rate a shorter fixed-rate period can reach without becoming more expensive overall than a longer fixed-rate period taken from the start. It's calculated by projecting the shorter option's remaining balance at the end of its fixed period forward at a rate that makes it meet the longer option's remaining balance at the same point in time. If the actual follow-up rate ends up below that figure, the shorter fixation was cheaper; above it, the longer fixation would have paid off. The comparison matters most when the premium for the longer fixation is small — then the break-even rate often sits well above today's market level, meaning the extra security costs very little in practice. The calculator below computes the break-even rate for your two offers. Not legal or tax advice.
Your comparison
One loan, two offers with different fixed-rate periods. Initial repayment rate is the same for both; the payment stays constant when moving into follow-up financing.
Non-binding model calculation. Assumes offer A's payment stays constant into follow-up financing, and equal initial repayment rates for both offers. The actual follow-up rate years from now is not known today.
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A lower rate alone doesn't say much if the fixed period is shorter — the shorter fixation carries a follow-up risk whose price is unknown today. The break-even rate makes the two offers comparable: it names the exact point at which betting on a cheap follow-up rate stops paying off.
In practice the comparison matters most when the premium for the longer fixation is small — often just 0.2 to 0.5 percentage points. Then the break-even rate often sits well above what's realistic in the market, and the extra security of the longer fixation costs very little in real terms.
A model, not a forecast
- The future rate is unknown. The break-even rate is a comparison figure, not a prediction. It doesn't tell you what the rate will actually be in ten years — only the level above which the shorter fixation turns out to have been more expensive in hindsight.
- Personal flexibility matters too. If you plan to sell, refinance, or make extra repayments in the coming years, weigh that more heavily than the pure interest math — shorter fixations are often more flexible in their terms.
- Creditworthiness can change. A long fixation locks in not just the rate but also financeability — relevant for foreseeable changes such as self-employment, retirement, or moving abroad.
We put the break-even rate into the context of your actual situation — including which bank offers both terms at all for your constellation.
Frequently asked questions
What is the break-even rate on a German mortgage?
Is the longer fixed-rate period always the safer choice?
Why is the break-even rate often higher than today's market rate?
Does the payment really stay the same in follow-up financing?
What if the calculator shows "no intersection"?
Information
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