What is an Interest Rate?

Whether you are considering a mortgage, looking at loan interest rates or wondering why your savings earn what they do, this article covers the essentials in plain language.

Interest rate definition: The basics

An interest rate is a percentage charged on borrowed money or paid on saved money over a set period, typically one year. Think of it as the price of using someone else’s money.

When you borrow, you pay interest to the lender. When you save, the bank pays interest to you. The rate determines how much that payment will be.

For example, if you borrow £1,000 at an annual interest rate of 5%, you would owe £50 in interest after one year (assuming simple interest). If you deposit £1,000 in a savings account at 5%, you would earn £50 over the same period.

The interest rate definition remains consistent across financial products, but how interest is calculated and applied can vary considerably. This is why understanding the basics matters before you sign any agreement.

How do interest rates work?

Interest rates work differently depending on whether you are borrowing or saving. Both sides of this equation affect your finances, often simultaneously.

Interest on borrowing

When you take out a loan, credit card or mortgage, you agree to repay the original amount (the principal) plus interest. The interest rate determines how much extra you pay for the privilege of borrowing.

Most loans use compound interest, meaning interest is charged on both the original amount and any previously accumulated interest. This is why borrowing costs can grow faster than you might expect if left unchecked.

Lenders set their rates based on several factors:

• The Bank of England base rate

• Their own funding costs

• Your creditworthiness

• The loan amount and term

• Whether the loan is secured against an asset

Higher-risk borrowers typically face higher rates. A secured loan, such as a mortgage backed by property, usually carries a lower rate than an unsecured personal loan because the lender has collateral.

Interest on savings

When you deposit money into a savings account, the bank uses your funds to lend to others. In return, they pay you interest. The rate you receive reflects the bank’s cost of attracting deposits and current market conditions.

The higher the bank interest rates on your account, the faster your savings grow. However, if the interest rate is lower than inflation, your money loses purchasing power over time even as the balance increases. This is a crucial consideration for long-term savers.

Savings accounts may pay interest monthly, quarterly or annually. More frequent payments benefit you slightly because of compounding, though the difference on smaller balances is modest.

The Bank of England base rate explained

The Bank of England base rate, often called the Bank Rate, is the single most influential interest rate in the UK economy. It is the rate at which the Bank of England lends to commercial banks overnight.

The Monetary Policy Committee (MPC) meets eight times a year to decide whether to raise, lower or hold the Bank Rate. Their primary aim is to keep inflation close to the government’s 2% target while supporting economic stability.

When the MPC changes the Bank Rate, the effects ripple through the entire financial system. Banks adjust their own lending and savings rates in response, though not always immediately or by the same amount.

How the base rate affects you

The Bank of England interest rate influences nearly every financial product you encounter. Here is how that connection works in practice:

Mortgages: Variable-rate and tracker mortgages respond directly to Bank Rate movements. A 0.25 percentage point rise in the Bank Rate typically leads to higher monthly payments for these borrowers.

Loans: Personal loan rates tend to follow the Bank Rate over time, though competition among lenders can soften or delay the effect.

Savings: Higher Bank Rates generally mean better returns on savings accounts, though banks may be quicker to raise borrowing rates than savings rates.

Credit cards: Rates on credit cards are less directly tied to the Bank Rate but can still shift in response to sustained changes.

The Bank Rate provides a baseline. Individual products vary based on the lender’s strategy, your personal circumstances and market competition.

Types of interest rates

Not all interest rates work the same way. Understanding the different types helps you compare products and anticipate how your costs or returns might change.

Fixed vs variable rates

Fixed rates remain constant for an agreed period, regardless of what happens to the Bank Rate or broader market conditions. You generally know what rate you will pay or earn throughout the fixed term, subject to the product’s terms and any applicable fees/charges. The trade-off is that you miss out if rates move in your favour.

Variable rates can change at any time, usually in response to movements in the Bank Rate. Your payments or earnings may go up or down. This offers flexibility but brings uncertainty.

Tracker rates are a specific type of variable rate that moves directly with a reference rate, typically the Bank Rate. If the Bank Rate rises by 0.25%, your tracker rate rises by the same amount.

Fixed vs variable interest rates comparison:

Neither type is inherently better. The right choice depends on your circumstances, risk tolerance and view of where rates might head. Past rate movements do not reliably indicate future direction.

APR and AER: What they mean

Two acronyms appear constantly when comparing financial products: APR and AER. They serve similar purposes but apply to different situations.

APR stands for Annual Percentage Rate. It applies to borrowing and includes both the interest rate and any mandatory fees, expressed as a yearly percentage. APR allows you to compare the true cost of loans, mortgages and credit cards on a like-for-like basis. Lenders must display a representative APR in their advertising.

AER stands for Annual Equivalent Rate. It applies to savings and shows the interest you would earn if your money was left in the account for a full year with interest compounded. AER makes comparing savings accounts straightforward, even when they pay interest at different intervals.

When comparing loan interest rates, look at the APR. When assessing what is the interest rate on a savings account, check the AER. These standardised figures exist precisely to help consumers make informed comparisons.

Current interest rates in the UK

Interest rates in the UK change over time in response to economic conditions. The Bank of England publishes its current Bank Rate on its official website, and this figure serves as the anchor for most other rates in the economy.

Current interest rates UK consumers encounter vary by product type:

Typical UK interest rate ranges by product:

*Illustrative only – ranges vary by provider, eligibility and product terms.

These ranges shift as the Bank Rate and competitive conditions change. Rates can also vary significantly between providers, so shopping around remains worthwhile.

Important: Interest rates can change at any time. Any specific rates you see today may not be available tomorrow. Past interest rates are not a reliable guide to future rates. Always check current rates directly with providers before making financial decisions.

Why do interest rates change?

Interest rates change because of decisions made by central banks, movements in financial markets and competitive pressures among lenders. Several factors drive these changes.

Inflation is the primary concern for the Bank of England. When prices rise too quickly, higher interest rates can slow spending and borrowing, which helps cool inflation. When inflation is low and economic growth is sluggish, lower rates can encourage borrowing and spending.

Economic growth also plays a role. A strong economy can support higher rates without choking off activity. A weakening economy may need lower rates to stimulate demand.

Global events affect UK rates too. International financial conditions, currency movements and events in major economies can influence what happens here.

Competition among lenders shapes the rates you actually see. Banks compete for customers, which can push mortgage or savings rates above or below where the Bank Rate alone would suggest.

Your personal circumstances matter as well. Lenders assess your credit history, income and existing debts when setting the rate they offer you. Two people applying for the same product may receive different rates.

Predicting future rate movements is difficult even for experts. The Bank of England does not pre-commit to future decisions, and unexpected events can shift the economic outlook rapidly.

How interest rates impact your finances

Interest rates affect your financial life in concrete ways. Understanding these impacts helps you plan and respond when rates change.

Mortgages and loans

For most people, their mortgage is their largest financial commitment. Even small changes in interest rates can have significant effects over a 25 or 30-year term.

Consider a £200,000 repayment mortgage over 25 years. A one percentage point increase in the interest rate adds thousands of pounds to the total amount repaid and increases monthly payments noticeably. The exact figures depend on the specific rate and terms.

If you have a variable or tracker mortgage, your payments change when rates change. Budgeting for potential increases is sensible, even if you hope rates will fall.

Fixed-rate mortgage holders are protected during their fixed term but face a new rate when that term ends. If rates have risen since you fixed, your new payments could be substantially higher.

Personal loans work similarly. Higher rates mean higher repayments and greater total cost. Before borrowing, calculate the total amount repayable, not just the monthly figure.

Savings and deposits

Higher interest rates benefit savers by increasing returns on deposits. After years of very low rates, recent increases have improved the outlook for those with cash savings.

However, the benefit depends on inflation. If your savings rate is 4% but inflation is 5%, your money still loses purchasing power in real terms. The nominal return (the number on your statement) is not the same as the real return (what your money can actually buy).

Different account types respond differently to rate changes:

• Easy-access accounts offer flexibility but often lower rates.

• Notice accounts require advance warning before withdrawals but may pay more.

• Fixed-term bonds lock your money away for a set period in exchange for a fixed rate (subject to the account’s terms and conditions).

Spreading savings across account types can balance access and returns, though this is a general observation rather than a recommendation for your specific situation.

Key takeaways

Understanding interest rates helps you navigate borrowing, saving and the broader economic environment. Here are the essential points:

• An interest rate is the percentage cost of borrowing money or the reward for saving it.

• The Bank of England Bank Rate is the UK’s benchmark rate and influences most other rates.

• Fixed rates offer certainty; variable rates can change with market conditions.

• APR shows the true cost of borrowing; AER shows the true return on savings.

• Interest rates change based on inflation, economic conditions and competition among lenders.

• Rate changes affect mortgages, loans and savings in tangible ways.

• Past rates do not predict future rates; conditions can change unexpectedly.

Interest rates can move in either direction, and individual circumstances vary widely. Before making significant financial decisions, consider how potential rate changes might affect your plans. General information like this article cannot replace advice tailored to your specific situation.

For the latest Bank Rate decision and detailed explanations, the Bank of England website provides authoritative and current information.