Mortgage interest rates: what they are and how they affect your monthly payments

Mortgage interest rates are one of the biggest drivers of how much you pay each month. But the “headline rate” is only part of the story. Understanding how different mortgage types set their interest—and what happens when your deal ends—can help you compare products more accurately.

This guide explains the main types of mortgage interest rates in the UK, what makes a rate look attractive, and how changes in interest rates can affect your mortgage over time.

What is a mortgage interest rate?

A mortgage interest rate is the cost of borrowing, expressed as a percentage of the loan amount. Lenders charge interest to cover their costs and make a profit.

When you receive a mortgage offer or illustration, the interest rate is usually shown alongside other important details such as:

• the product type (for example fixed or tracker)
• the deal term (how long the rate lasts)
• any early repayment charges if you leave the deal early
• the repayment structure (repayment or interest-only)

Even if two mortgages have similar headline rates, the overall cost can differ because of these other features.

The main types of mortgage interest rates

1) Fixed-rate mortgages

A fixed-rate mortgage keeps the interest rate the same for a set period—commonly 2, 3 or 5 years.

What this means for you

• Your monthly payment is typically more predictable during the fixed period.
• Your rate does not move up or down with changes in the wider economy while the fix is in place.

Common trade-off

• Fixed deals often include early repayment charges if you repay or refinance before the end of the fixed term.

2) Tracker mortgages

A tracker mortgage is designed to follow an external benchmark, most commonly the Bank of England base rate, plus a lender-set margin.

How it works

• If the benchmark rises, the mortgage interest rate usually rises too.
• If the benchmark falls, the mortgage interest rate usually falls.

What to look for

• The margin above the benchmark (this affects the level of your rate).
• Whether there are early repayment charges and how they apply.

Tracker products can be appealing when you expect interest rates to fall, but they can also increase your payments if rates rise.

3) Standard Variable Rate (SVR)

An SVR is the rate a lender sets at its discretion once a mortgage deal ends.

Key points

• The SVR can change at any time.
• It is often higher than the more competitive rates available on new deals.

For many borrowers, the SVR matters because it can be the rate you move onto after a fixed or tracker period ends—unless you remortgage.

4) Offset mortgages

An offset mortgage links your mortgage to savings. Instead of paying interest on your savings, the lender may use your savings balance to reduce the amount of mortgage interest you pay.

Why it can help

• If you hold savings, an offset arrangement can potentially reduce the effective interest cost.

What to check

• How the offset is calculated (and whether interest is calculated daily or monthly).
• Any product restrictions and how the savings and mortgage balances interact.

What is considered a “good” mortgage interest rate?

A “good” interest rate is not always the lowest one on the market. The best rate for you depends on how long you plan to keep the mortgage deal and how comfortable you are with payment changes.

Common ways borrowers judge whether a rate is “good” include:

• Affordability during the deal term: can you comfortably meet the payments if rates move?
• Total cost over time: does the product’s structure and any charges make it more expensive overall?
• Flexibility: how costly is it to leave the deal early?

For example:

• If you want payment stability, a fixed rate may be more suitable.
• If you expect to move or refinance sooner, you may prefer a product with features that reduce the cost of exiting.

Other factors to consider alongside your mortgage interest rate

Mortgage product term

The length of the deal (for example 2-year vs 5-year) can influence the rate offered. Lenders price products based on expected interest rate conditions and their own risk.

A longer fixed term can sometimes provide more certainty, while a shorter term may offer the opportunity to remortgage sooner if conditions change.

Early repayment charges (ERCs)

If you repay your mortgage early—either by selling the property, switching lenders, or refinancing—some products apply early repayment charges.

These charges can be significant, so it’s important to consider:

• whether ERCs apply during the whole deal term or only in certain periods
• how they are calculated (for example, a percentage of the outstanding balance)
• how likely you are to move or change your mortgage before the deal ends

The interest rate is not the whole cost

Mortgage illustrations and quotes may also include other costs and features that affect the overall picture, such as:

• arrangement or product fees (where applicable)
• whether the mortgage is repayment or interest-only
• the overall loan-to-value (LTV) and how that influences pricing

How changes in interest rates can impact your mortgage

Fixed-rate mortgages

During the fixed period, your interest rate is set. Wider economic changes generally do not affect your mortgage payments while the fix lasts.

The main risk for fixed-rate borrowers is what happens when the deal ends—for example moving onto SVR or needing to remortgage.

Tracker mortgages and SVR

Tracker rates move with the benchmark they follow, and SVR can change according to the lender’s decisions. In both cases, your payments can increase or decrease over time.

Offset mortgages

Offset arrangements can be affected by changes in both mortgage interest and savings interest. If savings rates rise, the offset benefit may improve; if savings rates fall, the benefit may reduce.

Comparing mortgage rates more effectively

When reviewing mortgage options, it can help to compare beyond the headline number. A practical approach is to consider:

• What type of rate is it? (fixed, tracker, SVR, offset)
• How long is the deal term?
• What happens at the end of the deal?
• Are there early repayment charges?
• How would your payments change if rates move (where relevant)

This can make it easier to spot products that look cheap at first glance but may cost more depending on your timeframe.

Mortgage interest rates and different borrower needs

Interest rates affect borrowers differently depending on their situation. For example, someone who plans to stay in the property for a long period may prioritise stability, while someone expecting to move sooner may focus on flexibility and exit costs.

If you are comparing options across different mortgage types, it’s worth thinking about how your plans could change over the deal term and how that interacts with the rate structure.

Important note

Mortgage interest rates and the cost of borrowing can change over time. The right mortgage product depends on your individual circumstances, including your income, deposit, property value, and plans for the future.

If you’re reviewing mortgage options, make sure you understand the full terms of any product you consider, including how and when the interest rate can change and whether any early repayment charges apply.