A 1% rate change typically moves your monthly payment by $100 to $200 per $100,000 borrowed

The exact amount depends on three things: how much you borrowed, how many years you have to repay it, and where your rate starts. On a $300,000 loan over 30 years, moving from 6% to 7% raises your monthly payment by roughly $200. The same 1% jump on a $200,000 loan costs about $130 more per month. On a smaller $150,000 loan, expect roughly $100 extra.

The reason the payment jumps is that interest compounds over time. When your rate is higher, more of each payment goes toward interest instead of building equity in your home. Early in the loan, this effect is strongest — a rate change in year one affects 360 payments, not just one.

You can calculate your own number using a mortgage calculator (search "mortgage payment calculator" and enter your loan amount, term, and both interest rates). The difference between the two monthly payments is what that 1% costs you.

Key Takeaways

  • A 1% interest rate increase typically raises your monthly payment by $100 to $200 for every $100,000 you borrow on a 30-year loan.
  • The impact is larger on bigger loans and smaller on shorter loan terms, because the rate change affects more total payments.
  • Higher rates mean more of your early payments go to interest rather than building equity in your home.
  • You can see the exact impact on your situation by entering your loan amount, term, and both rates into a mortgage calculator.

Why the same 1% costs different amounts for different people

The size of your loan is the biggest factor. A 1% rate jump on $500,000 costs roughly $330 more per month, while the same jump on $100,000 costs roughly $65 more. The larger the borrowed amount, the larger the dollar impact.

The length of your loan also matters. A 15-year mortgage is paid off faster, so a 1% rate change affects fewer total payments. On a $300,000 loan, moving from 6% to 7% costs about $280 extra per month on a 15-year term, compared to $200 on a 30-year term. Shorter loans already have higher monthly payments, so the rate change is a smaller percentage increase — but the dollar amount is still significant.

Where you start also shifts the impact slightly. A 1% jump from 3% to 4% has a different effect than a jump from 6% to 7%, because the math of compounding works differently at different rate levels. At lower starting rates, the percentage increase in your payment is larger. At higher starting rates, the dollar increase is larger but the percentage increase is smaller.

How lenders calculate the payment when rates change

Your mortgage payment covers two things: principal (the amount you borrowed) and interest (what the lender charges for lending it). The lender uses a formula that spreads both across your entire loan term so your payment stays the same every month.

When the interest rate goes up, the lender recalculates that formula. More of each payment now goes to interest, so less goes to principal. To keep the loan paid off in the same number of years, the total payment has to rise. The lender's calculator does this automatically — you do not have to understand the math, only that a higher rate means a higher payment.

This is why shopping for a lower rate matters so much. Even a 0.5% difference saves you tens of thousands of dollars over 30 years, because that savings compounds across hundreds of payments.

What a 1% change means for your total cost over the life of the loan

The monthly payment is only part of the picture. Over 30 years, a 1% rate increase costs you far more than 12 times the monthly difference.

On a $300,000 loan, a 1% rate jump from 6% to 7% raises your monthly payment by about $200. That sounds like $2,400 per year. But over 30 years, you pay roughly $72,000 more in total interest. The reason is that every extra dollar of interest in year one compounds into more interest in year two, and so on.

This is why even small rate differences matter when you are shopping for a mortgage. A 0.25% difference might seem tiny, but it saves you roughly $18,000 over 30 years on a $300,000 loan.

How to see the impact before you commit to a rate

Most lenders let you lock in a rate for a set period — usually 30, 45, or 60 days — while your loan is being processed. During that lock, your rate cannot change even if market rates move. This gives you time to shop without worrying that rates will jump between the time you explore and the time you close.

Before you lock, ask your lender to show you the payment at your quoted rate and at rates 0.5% and 1% higher. This shows you what happens if rates move before you can lock, or if you decide to accept a higher rate in exchange for lower upfront costs (called "points"). Many lenders provide this comparison without charging you.

You can also run the numbers yourself using any mortgage calculator. The goal is to understand your own situation — what payment you can afford, and how much rate movement would change that.

The difference between fixed and adjustable rates

A fixed-rate mortgage locks your interest rate for the entire loan term — 15, 20, or 30 years. Your payment never changes, no matter what happens to market rates. A 1% rate change at the time you close affects your payment, but nothing that happens after closing does.

An adjustable-rate mortgage (ARM) starts with a lower rate for a set period (often 3, 5, 7, or 10 years), then adjusts periodically based on market rates. If rates rise 1% when your ARM adjusts, your payment rises the same way it would on a fixed loan — but now you are locked into that higher payment for the next adjustment period. ARMs are riskier because you cannot predict your payment after the initial period ends.

Most first-time borrowers choose fixed rates because the payment is predictable. If you are considering an ARM, make sure you understand what your payment could be at the highest rate your loan allows, and whether you could afford that.

Frequently Asked Questions

Does a 1% rate increase affect a 15-year loan the same way as a 30-year loan?

No. The monthly payment increase is smaller on a 15-year loan because you are paying off the principal faster. On a $300,000 loan, a 1% jump costs about $280 more per month on a 15-year term versus $200 on a 30-year term. However, the total interest you pay over the life of the loan increases more on the 15-year loan because you are paying a higher rate on a larger balance for longer.

If I lock my rate, can it change before I close?

No. Once your rate is locked, it stays the same through the closing date, even if market rates move. If your lock period expires before closing and you have not closed yet, your lender may offer to extend the lock, usually for a fee. Always confirm your lock period in writing when you explore.

Can I refinance if rates drop after I close?

Yes. Refinancing means taking out a new loan to pay off your old one. If rates drop 1% or more, refinancing may save you money, though you will pay closing costs again (typically 2% to 5% of the loan amount). A lender can tell you whether refinancing makes sense for your situation by comparing your savings against those costs.

What if I want to pay off my mortgage faster — does a higher rate cost me more?

Yes. If you pay extra toward principal each month, a higher rate still costs you more in total interest, even though you are paying the loan off faster. The benefit of paying extra is that you reduce the number of years you pay interest at all. A mortgage calculator can show you how much faster you would pay off the loan if you add extra payments.

How much does a 0.5% rate change cost compared to 1%?

A 0.5% change costs roughly half what a 1% change costs. On a $300,000 loan over 30 years, moving from 6% to 6.5% raises your payment by about $100 per month, compared to $200 for a full 1% jump. Over 30 years, a 0.5% difference saves roughly $36,000 in interest.