Mortgage Rate Change Calculator
How much does a mortgage rate change actually affect your payment? Enter one loan amount and term, put two interest rates side by side, and Fetch will show the monthly, yearly and lifetime difference in plain dollars.
Method and copy last reviewed · How our calculations work
Your numbers
Same loan amount and same term in both columns — only the interest rate changes.
The mortgage balance, not the purchase price
Typically 30, 20 or 15 years
The rate you have or have been quoted
The rate you want to test against it
What the rate difference costs
Extra per month at the higher rate
$132.94
6.5% vs 7% on $400,000.00 over 30 years
| Interest rate | Monthly P&I | Total interest | Total paid |
|---|---|---|---|
| 6.5%First rate | $2,528.27 | $510,179.82 | $910,179.82 |
| 7%Comparison rate | $2,661.21 | $558,035.91 | $958,035.91 |
- Monthly difference
- $132.94
- Difference per year
- $1,595.28
- Total interest over 30 years
- $47,856.09
Principal and interest only
Twelve monthly payments
Difference between the two rates
These figures cover principal and interest only, on a fixed-rate loan held for the full term. Property tax, homeowners insurance, HOA dues and mortgage insurance are not included here — they are the same in both columns, so leaving them out keeps the difference attributable to the rate. All results are estimates; a real lender quote depends on fees, points, credit and the property, so compare actual Loan Estimates before deciding anything.
Ask Fetch
Ask about your numbers
Fetch explains your results in plain English. Every number comes from re-running the calculator above, so the figures are exact — never generated.
Why a fraction of a percent matters
A mortgage is unusual in two ways: the balance is large, and you keep it for decades. Both of those multiply the effect of the rate. A quarter of a percent sounds like a rounding error, but it is charged every month on a balance that takes years to come down, so it shows up twice — once in the payment you have to fit into your budget, and again in the total interest you hand over before the loan is gone.
That is also why the same rate move lands differently on different loans. On a smaller balance or a shorter term the dollar gap is modest. On a large 30-year loan the same fraction of a percent can change the payment by an amount that decides whether a house is affordable at all. Rather than rely on a general rule, put your own amount and term in above.
This page carries no market rate and makes no forecast. Rates change constantly, and what they do next is not something we or anyone else can tell you. What we can do is turn any two rates you are weighing into the numbers that actually affect your budget.
How to use the comparison
Testing a quoted rate. Put the rate you have been offered in the first field and a rival quote in the second. The monthly difference is your immediate budget impact; the total-interest difference is what the cheaper quote is really worth if you keep the loan.
Testing a what-if. Leave your rate in the first field and try a quarter or half point either side in the second. That shows how much room a rate move gives or takes away before you commit to a price range.
Then see the full picture. This tool is rate-only. For principal, interest, property tax, insurance, HOA and PMI in one monthly number, use the mortgage calculator. If the two offers differ in more than the rate — different fees, term or loan amount — compare them properly in the loan comparison calculator, and check the effect of fees in the APR calculator.
Frequently asked questions
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FetchCalc is an independent calculator and educational service. We are not a lender, broker, or financial adviser, and nothing here is financial advice. Estimates are for planning only; your actual offer and payment will come from your lender.