Break My Mortgage Calculator

What the Break My Mortgage Calculator does

A penalty calculator tells you what breaking costs. That is only half the question. What people actually want to know is whether it is worth it — whether the interest saved at a lower rate is bigger than the penalty and fees it takes to get there. This page answers that, and gives you a verdict rather than a number to interpret on your own.

It also refuses to pretend it knows what rates will do. The single biggest factor in whether waiting beats breaking is the rate you will be offered at your renewal date, and nobody can tell you that. So it is a control you can move, and the calculator solves for the exact renewal rate at which waiting stops being cheaper — a threshold you can watch for, rather than a forecast you have to trust.

• A verdict — break, stay, or too close to call — with the reasoning shown
• Your net benefit in dollars, and the break-even point in months against the time you actually have left
• Three options costed over the same horizon: break now, stay to renewal, or blend and extend
• The penalty under both lender methods, so you can see which one you are facing
• The crossover renewal rate where waiting and breaking cost exactly the same

Why breaking a fixed mortgage so rarely pays off

This is the part most calculators leave out, and it is the single most useful thing on the page.

An interest rate differential is not an arbitrary fee. It is designed to recover exactly the interest your lender gives up by letting you leave early. Because of that, it cancels almost precisely the interest you would save — and it grows as your saving grows. Find a rate half a point lower and the penalty rises to match it. On a fixed mortgage where the IRD is the binding charge, your net benefit stays pinned at roughly minus the fees no matter how good a rate you go and find.

That is why the answer to "should I break my fixed mortgage for a better rate" is usually no, and why shopping harder for a rate does not change it. Breaking pays off when the IRD is not what is being charged: on a variable mortgage, where the penalty is three months’ interest and nothing more; when few enough months remain that three months’ interest is the greater figure; or when the rate you can genuinely get is below the comparison rate your lender uses in its own formula.

• The IRD recovers the lender’s lost interest, so it offsets your saving almost exactly
• A larger rate drop raises the penalty in step — it does not improve the outcome
• Variable mortgages are charged three months’ interest only, with no IRD at all
• Late in a term, three months’ interest becomes the greater charge and breaking gets easier
• The calculator flags when your penalty is cancelling your saving, so you know shopping harder will not help

The variables that move the answer

Four inputs decide this, and the one people get wrong is the one that is not on their statement.

• The rate gap — the whole saving comes from the difference between your current rate and the new one, applied to your balance across the months you have left. A small gap on a large balance can still be worth it; a large gap close to renewal usually is not.
• Months remaining — this cuts both ways, which is why it cannot be reasoned about in your head. More months left means more interest you would save, but also a larger IRD, because the differential scales with the time remaining.
• Lender type — a big bank’s posted-rate method nets its posted rate against the discount you negotiated at signing, and typically produces the largest penalty of any method. A monoline or credit union usually uses the standard method against today’s market rate.
• The rate at your renewal — genuinely unknowable, and the honest way to handle it is as a slider with a stated crossover, not a number quietly baked into the result. Lenders price renewals off the market at the time and have no obligation to relate the offer to your original rate.

How this is actually calculated

The penalty is the greater of three months’ interest and the interest rate differential, calculated under whichever method your lender type uses — the same engine as the blend-and-extend page, so the two never disagree.

All three options are then costed over one common horizon: the new term you would lock in by breaking. Cost is measured as the cash you part with over that horizon plus the balance you still owe at the end of it. That definition matters. It means an option cannot look cheap simply by leaving you owing more, and it prices a financed penalty correctly — financing shows up as extra interest, paying cash shows up as cash, and neither is counted twice.

Staying is modelled in two phases: your current rate for the months left in your term, then your assumed renewal rate for the rest of the horizon. Blend and extend weights your current rate and the new rate by the months each applies for, with no penalty charged. The crossover rate is then solved by bisection — narrowing in on the renewal rate where staying and breaking come to exactly the same total.

• Penalty: the greater of three months’ interest and the IRD, by your lender’s method
• Cost over the horizon: cash paid plus the balance still owed, netted against the balance every option starts from
• Stay: your current rate to renewal, then the assumed renewal rate for the remainder
• Blend: (current rate × months remaining + new rate × extension months) ÷ total months, penalty-free
• Semi-annual compounding for fixed rates, monthly for variable, as the Interest Act requires

Using your results well

Start with the exact figures from your mortgage statement — the balance, the contract rate, and the precise number of months left. The penalty scales directly with the months remaining, so an estimate there moves the answer more than anything else on the page.

Then get an official payout statement before you act. The penalty here is built from the numbers you entered and the standard formulas; the binding amount is set by your mortgage contract, and under the posted-rate method the gap between an estimate and the real figure can run into thousands. No calculator can substitute for that statement.

And note what the math deliberately cannot weigh: whether you are certain you will stay in the home, whether you might sell before the new term ends, or whether a lower payment solves a cash-flow problem today that is worth paying for regardless of the break-even point. Those are legitimate reasons to break or stay that no spreadsheet prices.

• Use the exact balance, rate and months remaining from your statement
• Request an official payout statement before committing to anything
• Check whether your lender will cover legal and appraisal costs on a straight switch — many will
• Compare the blend-and-extend figure carefully; it avoids the penalty entirely and often wins
• Move the renewal-rate control and see how close your numbers sit to the crossover