Mortgage refinance calculator:
will the new loan repay its own fees?

What a mortgage refinance calculator compares

Refinancing swaps your existing mortgage for a new loan, usually at a different rate, a different tenure, or both. A refinance calculator puts today's loan beside the proposed one and includes what it costs to switch.

Two checks decide whether it is worth it. The first is break-even: how many months of savings it takes to recover the fees. The second is total cost: whether you pay less in all, measured to the same end date.

Many offers pass the first check and fail the second, because a lower monthly payment is often just a longer loan.

You need five figures: the outstanding balance, the current rate and months remaining, the proposed rate and tenure, and the total cost of switching. The balance and months left come from your latest statement. The cost has to come from the new lender in writing, because it is the figure most often left out.

Refinancing makes the most sense when the rate gap is meaningful, a good part of the tenure is still ahead and you expect to hold the loan for years. It makes the least sense late in a loan, when most of each EMI is already principal and there is little interest left to save.

Refinance break-even formula

1. 1List every cost of switching, from both lenders, in rupees.
2. 2Work out the new payment on the same outstanding balance.
3. 3Subtract it from your current payment to get the monthly saving.
4. 4Divide the costs by the monthly saving to get break-even months.
5. 5Compare break-even with how long you realistically expect to keep the loan.
6. 6Finish with the net saving formula, using the same end date for both loans.

If the new payment is higher than the current one, the denominator is negative and there is no break-even. That is not a mistake: it usually means a shorter tenure, where the point of switching is to finish sooner and pay less interest overall.

Worked example: ₹90,000 of costs, ₹3,000 saved a month

Timing decides everything. If you sell or switch again after 24 months you have saved ₹72,000 against ₹90,000 of fees, a net loss of ₹18,000. Keep the loan for 60 months and you are ₹90,000 ahead in simple cash terms.

This simple test ignores two things. Money has a time value, so ₹3,000 saved in month 30 is worth a little less than ₹3,000 today. And it treats both loans as ending together, which the next section shows is often false. Use it as a first filter, then run the fuller comparison.

Compare three outcomes before deciding: switch and stay for 60 months, switch and leave at 24 months, and stay put. The middle one is the downside case, so treat it as the number to be comfortable with.

Lower EMI or lower total cost?

Here is the trap, on one balance. Suppose ₹30,00,000 is outstanding on a loan at an assumed 9% with 12 years left. A lender offers an assumed 8.5% and ₹90,000 of total costs. The table compares four ways to proceed.

Read the table by end date. Rows one and two both finish in 144 months, so that comparison is clean. Row three runs 96 months longer: it feels cheaper every month but costs far more in total. Row four finishes six months early by keeping your payment high, which is why it wins.

The 20-year option cuts the payment by ₹8,106 a month yet costs about ₹14.2 lakh more overall. On the same 12-year term the saving is only ₹839 a month, so ₹90,000 of costs takes about 107 months to recover, roughly 9 of the 12 remaining years.

Keeping the new loan on your old EMI of ₹34,141 clears it in 138 months and is the cheapest of the four. The lesson is to compare to a common end date, not to compare EMIs.

Costs to include before you switch

A refinance quote is only as honest as its cost list. Ask both lenders for a written statement of every charge and add them up.

• Processing or login fee on the new loan.
• Legal, valuation and documentation charges.
• Foreclosure or prepayment charge on the old loan, if your agreement has one.
• Any registration or re-recording cost for the property documents.
• Insurance or other products the new lender requires you to take.

Also ask what the new lender will charge if you want to prepay later. A switch that comes with a heavy closing charge removes the flexibility you may want in the second half of the loan.

Where a lender offers to waive fees, check whether the rate was raised to pay for it. The break-even test works on whatever package you are actually offered, so run it on the final written quote, not the brochure.

Refinance mistakes that distort the result

• Comparing EMIs without comparing tenures, so a longer loan looks like a saving.
• Quoting an introductory or teaser rate and ignoring the rate that applies after it resets.
• Restarting a 20-year clock on a loan that has only 12 years to run.
• Treating break-even as a guarantee: if you sell or move before it, the switch has lost money.
• Leaving the old loan's closing charges out of the cost total.

Several of these errors are about timing rather than arithmetic. A refinance has a fixed cost today and savings spread over years, so the question is always how long you will stay in the loan. That is a personal forecast, not a number a calculator can supply.

If your realistic holding period is shorter than break-even, stay put even though the EMI falls. If you are weighing the new loan against simply prepaying the old one, the extra mortgage payments guide covers that comparison.