AtlasCalcsUtility Calculation Suite
2026-08-07 9 min

UK Mortgage Calculator

Calculate UK mortgage repayments with repayment or interest-only modes, monthly, bi-weekly, and weekly frequencies, LTV, overpayment comparison, and full amortization schedules in pounds sterling.

Calculator

Property Price
£
Deposit Amount
£
Mortgage Term(years)
years
Interest Rate(%)
%
Interest Type
Repayment Type
Repayment Interest-Only
Payment Frequency
Monthly Bi-Weekly Weekly
Extra Monthly Payment
£
Summary:Deposit: £60,000.00 (20.0%)Loan: £240,000.00 (80.0% LTV)
Results update live as you type

Results

Caution

Enter Valid Values

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Check the property price and term

Estimates assume a constant interest rate over the full term with on-time payments. Arrangement fees, valuation fees, legal costs, and stamp duty are not included. Interest-only results assume the capital is repaid separately.

Formula

The loan amount P is the property price minus the deposit. The periodic rate i is the annual rate divided by the payments per year (12 monthly, 26 bi-weekly, or 52 weekly). The annuity formula returns the fixed payment PMT that repays the loan over n periods, and the schedule is then run period by period to total the interest.

PMT = P × i(1+i)^n / ((1+i)^n − 1)

Alternative Form

Interest-only: PMT = P × i

Variables

SymbolNameUnitDescription
PLoan amountGBPProperty price minus the deposit
iPeriodic interest ratedecimal per periodAnnual rate divided by payments per year
nTotal payment periodsperiodsTerm years × payments per year
PMTPeriodic paymentGBPThe fixed amount paid each period
LTVLoan-to-value%Loan amount as a share of the property price
ExtraOverpayment per periodGBPExtra monthly payment converted to the chosen frequency

Explanation

UK repayment mortgages use the standard annuity formula: each payment covers the interest accrued since the last payment plus a slice of capital. Interest-only deals simply pay P × i every period and leave the capital untouched until the term ends. Because the periodic rate depends on the payment frequency, bi-weekly and weekly payments shave interest compared with monthly.

Derivation

The periodic rate is i = annualRate / periodsPerYear. For repayment deals the payment solves P = PMT × (1 − (1 + i)^−n) / i, giving PMT = P × i(1+i)^n / ((1+i)^n − 1). The schedule iterates n periods: interest = balance × i, principal = payment − interest, balance = balance − principal, stopping when the balance is fully repaid.

Worked Examples

See how the calculator works with different scenarios.

Scenario

A £300,000 home with a £60,000 deposit (20%) at 4.5% over 25 years, paid monthly.

Inputs

Property Price:£300,000
Deposit:£60,000 (20%)
Rate:4.5%
Term:25 years
Type:Repayment, monthly

Calculation

Loan = 300000 − 60000 = £240,000 i = 0.045 / 12 = 0.00375 n = 25 × 12 = 300 PMT = 240000 × 0.00375(1.00375)^300 / ((1.00375)^300 − 1) = £1,333.44

Result

£1,333.44 per month; £400,033 total payable; £160,033 total interest over 25 years

Interpretation

The £240,000 loan costs about £160,000 in interest — roughly two-thirds of the loan value. LTV of 80% puts the borrower in the tier most likely to be offered the best rates.

Understanding Your Result

Your Result: Enter Valid Values: ---

Typical range: UK fixed rates have ranged from about 4% to 6.5% in recent years depending on the term length and LTV tier. A 25-year repayment deal at 5% costs roughly £5.85 per month per £1,000 borrowed, and total interest is commonly 60-90% of the loan amount.

What This Means

The primary result is the periodic payment at your chosen frequency, followed by the total amount payable, total interest, loan amount, and LTV. When an overpayment is entered, the interest saved appears as an extra result.

Why It Matters

UK mortgage costs depend heavily on deposit size (LTV tier), the product rate, and payment frequency. Comparing repayment vs interest-only and monthly vs bi-weekly shows the real difference in total interest — often tens of thousands of pounds on the same loan.

Professional Interpretation

Lenders assess affordability with income multiples of 4-4.5× and stress tests near 3% above the product rate. The LTV tier determines which rates you are offered, and the payment shown here is one input to those affordability checks.

LTV tiers

Rates are banded by LTV: 60%, 75%, 80%, 85%, 90% and 95% tiers are common. A 5% deposit shift can change the rate by 0.1-0.3%, worth thousands over a 25-year term.

Overpayment allowances

Most UK lenders allow up to 10% of the outstanding balance per year without penalty. Above that, Early Repayment Charges (usually 1-5% of the amount repaid) apply during the deal period.

Recommendations

  • •Put down 20% or more to reach the best LTV rate tiers
  • •Run repayment vs interest-only scenarios before choosing
  • •Make overpayments within your 10% annual allowance
  • •Remortgage to a new deal when the initial rate period ends
  • •Consider bi-weekly payments to trim total interest
  • •Add stamp duty and fees to your budget before committing

Educational Content

Introduction

The UK Mortgage Calculator estimates monthly repayments from the property price, deposit, interest rate, and term, with repayment vs interest-only modes and monthly, bi-weekly, or weekly frequencies. It also models monthly overpayments and the interest they save.

Concept Explanation

A UK mortgage is a secured loan repaid over 15-35 years, most commonly 25. Repayment deals combine interest and capital in every payment; interest-only deals pay interest alone. Rates come as fixed deals (2, 3, or 5 years) or variable deals that track the Bank of England base rate.

Applications

▸Estimating repayments before house hunting
▸Comparing repayment vs interest-only structures
▸Checking how deposit size changes LTV and payment
▸Modeling overpayments within the 10% annual allowance
▸Comparing monthly, bi-weekly, and weekly frequencies
▸Budgeting total interest before committing to a term
▸Preparing for remortgaging at the end of a deal

Benefits

  • •Repayment and interest-only modes in one tool
  • •Monthly, bi-weekly, and weekly frequencies
  • •LTV calculation to judge rate eligibility
  • •Full amortization schedule with annual and periodic views
  • •Overpayment comparison with exact interest saved
  • •GBP formatting for UK budgeting

Limitations

  • •Assumes a constant rate over the full term
  • •Does not include fees, arrangement costs, or insurance
  • •Interest-only results assume capital is repaid elsewhere
  • •Does not model tracker margins or base-rate changes
  • •Overpayment runs assume the allowance is never exceeded

Best Practices

  • •Compare at least two LTV scenarios when saving a deposit
  • •Run overpayment scenarios within your allowance before overpaying
  • •Model the rate you would pay at renewal, not just today
  • •Check ERC terms before overpaying inside a fixed deal
  • •Budget SDLT and fees separately from the mortgage payment

Common Misconceptions

Myth: Interest-only mortgages are cheaper.
Truth: The monthly payment is lower, but no capital is repaid — you must fund the full loan separately at term end, and total interest is far higher.
Myth: A 5% mortgage costs 5% interest.
Truth: Total interest depends on the schedule and term. A 25-year repayment loan at 5% typically adds 60-90% of the loan in interest.
Myth: You can overpay as much as you like.
Truth: Most UK lenders cap penalty-free overpayments at 10% of the outstanding balance per year; anything more triggers Early Repayment Charges.
Myth: LTV does not matter once you are approved.
Truth: LTV drives the rate you are offered. Moving from 90% to 80% LTV often cuts the rate, saving thousands over the term.

Practical Tips

  • •A 5% larger deposit can drop you into a better LTV band — run both scenarios before buying
  • •Overpayments made early in the term save the most interest because the balance is largest
  • •Bi-weekly and weekly payments reduce accrued interest slightly vs monthly at the same rate
  • •Interest-only numbers look attractive but you must budget a separate repayment vehicle
  • •Remortgage 3-6 months before your fixed deal ends to avoid reverting to the SVR
  • •Add stamp duty and fees to the total cost when comparing properties
  • •Use the overpayment comparison to check you stay inside the 10% annual allowance

Common Mistakes

Choosing interest-only to lower the payment
Check both modes: interest-only leaves the full capital outstanding and usually costs more in total interest over the term.
Ignoring the LTV tier
A 95% LTV loan is priced very differently from 75%. Calculate LTV before comparing rates from lenders.
Comparing monthly and bi-weekly totals as equal
Bi-weekly payments accrue slightly less interest; compare total payable, not the per-period amount.
Overpaying without checking the allowance
Staying inside the 10% annual overpayment limit avoids ERCs that can erase the savings.
Forgetting the rate resets at the end of the deal
Most UK mortgages revert to the SVR after the initial deal. Recompute at a realistic renewal rate.
Using a US mortgage calculator for a UK loan
US tools omit UK structures like interest-only products, stamp duty SDLT, and the 10% overpayment allowance. Use a UK-specific calculator.

Assumptions

This calculator makes the following assumptions to provide estimates:

Constant Rate: The interest rate is fixed for the entire term. Real rates reset at each deal period end.
On-Time Payments: Every payment is made exactly on schedule; late payments change the interest accrued.
No Product Fees: Arrangement fees, valuation fees, and legal costs are not included in the totals.
Overpayment Within Allowance: Overpayments assume the 10% annual penalty-free limit is respected.
Interest-Only Vehicle: For interest-only deals, the capital is assumed to be repaid separately at term end.

Limitations

Be aware of these limitations when using this calculator:

Fixed Rate Only: Tracker margins and base-rate changes are not modeled; recompute when rates move.
No Stamp Duty or Fees: SDLT, legal fees, and mortgage arrangement fees are excluded from all results.
No Insurance: Buildings and life cover are not included in the repayment figure.
ERC Not Modeled: Early Repayment Charges for overpayments above the allowance are not computed.
Affordability Informational: Income multiples and stress tests are lender checks that this calculator does not perform.

Frequently Asked Questions

Answers to common questions about this calculator.

How does a UK mortgage differ from a US mortgage?
UK mortgages do not require Private Mortgage Insurance (PMI). Most are repayment or interest-only. Stamp Duty Land Tax applies on purchases over thresholds, and schemes like Help to Buy ISAs and Lifetime ISAs help first-time buyers with deposits.
What is the difference between repayment and interest-only mortgages?
With a repayment mortgage, monthly payments cover both interest and capital, paying off the loan by term end. With an interest-only mortgage, only interest is paid monthly; the loan amount stays unchanged and must be repaid separately at term end.
How is my monthly mortgage payment calculated?
Monthly payments use the amortization formula: M = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate, and n is the total number of payments. This calculator handles different payment frequencies.
What is Stamp Duty Land Tax (SDLT)?
SDLT is a tax paid when purchasing property over certain thresholds in England and Northern Ireland. Rates range from 0% on purchases up to £250,000 (£425,000 for first-time buyers) to 12% on portions above £1.5 million. Scotland and Wales have separate systems.
What is the typical mortgage term in the UK?
The most common mortgage term in the UK is 25 years, though terms range from 15 to 35 years or longer. Shorter terms mean higher monthly payments but less total interest. Longer terms reduce monthly payments but increase total interest costs.
What deposit do I need for a UK mortgage?
Most lenders require at least 5-10% deposit (95-90% LTV). A 20% deposit (80% LTV) typically gets you the best interest rates. First-time buyers may qualify for schemes requiring as little as 5% deposit through government-backed programs.
What is loan-to-value (LTV) ratio?
LTV is the loan amount divided by the property value, expressed as a percentage. A £240,000 loan on a £300,000 property equals 80% LTV. Lower LTV ratios (under 80%) qualify for better interest rates and may not require a higher rate adjustment.
What is the difference between fixed-rate and variable-rate mortgages?
Fixed-rate mortgages lock your interest rate for a set period (2, 3, or 5 years typically), providing payment certainty. Variable-rate mortgages can change with the Bank of England base rate, potentially offering lower initial rates but with payment uncertainty.
What is a tracker mortgage?
A tracker mortgage follows the Bank of England base rate plus a fixed margin (e.g., base rate + 1.5%). When the base rate changes, your payments adjust accordingly. Trackers often have lower initial rates than fixed deals but carry interest rate risk.
What is a Standard Variable Rate (SVR)?
SVR is the default interest rate a lender applies after your initial deal period ends. SVRs are typically higher than introductory rates. It is usually advisable to remortgage to a new deal when your initial period expires rather than staying on the SVR.
Can I make overpayments on my UK mortgage?
Most UK lenders allow overpayments of up to 10% of the outstanding balance annually without penalty. Overpayments reduce the principal directly, saving interest and shortening the term. Exceeding the limit may incur Early Repayment Charges (ERCs).
What are Early Repayment Charges (ERCs)?
ERCs are fees charged if you repay more than the permitted overpayment amount during a fixed-rate or tracker deal period. ERCs typically range from 1-5% of the amount repaid. They usually apply only during the initial deal period, not after it ends.
How does making overpayments save money?
Overpayments reduce the outstanding capital, meaning future interest is calculated on a smaller balance. For example, overpaying £100 monthly on a £240,000 mortgage at 4.5% could save over £30,000 in interest and reduce the term by several years.
What is a Help to Buy ISA?
The Help to Buy ISA was a government scheme (closed to new accounts November 2019) allowing first-time buyers to save up to £200 monthly with a 25% government bonus (up to £3,000) when purchasing a first home. Existing account holders can continue saving.
What is a Lifetime ISA (LISA)?
A Lifetime ISA is available to adults aged 18-39. You can save up to £4,000 per year, and the government adds a 25% bonus (up to £1,000 per year). Funds can be used for a first home purchase (up to £450,000) or retirement after age 60.
What is Shared Ownership?
Shared Ownership lets you buy a share of a property (typically 25-75%) and pay rent on the remaining share. You can buy more shares later through staircasing. It is designed to help people who cannot afford to buy a home on the open market.
What is the First Homes Scheme?
The First Homes Scheme offers newly built homes at a discount of at least 30% for local first-time buyers and key workers. The discount is preserved when the home is sold, ensuring it remains affordable for future first-time buyers.
How do I qualify for a UK mortgage?
Lenders assess affordability based on income, credit history, deposit size, and monthly expenses. Most lenders offer up to 4-4.5 times your annual income. A strong credit score, stable employment, and a larger deposit improve your chances and rates.
What is mortgage affordability?
Mortgage affordability is how much a lender is willing to lend you based on your income, outgoings, and credit history. Lenders stress-test at higher rates (typically 3% above the product rate) to ensure you can afford payments if rates rise.
What credit score do I need for a UK mortgage?
Most lenders prefer a credit score of 700+ (out of 999). Lower scores may still qualify but with higher rates. Check your credit report with Experian, Equifax, or TransUnion for errors before applying.
What is the Bank of England base rate?
The Bank of England base rate is the official interest rate set by the Monetary Policy Committee. It influences mortgage rates across the UK. When the base rate rises, variable and tracker mortgage rates typically increase, while fixed rates may also rise.
Should I fix my mortgage rate?
Fixing provides payment certainty and protection against rate rises. It is advisable if you prefer predictable payments or believe rates will rise. Consider your risk tolerance, financial situation, and how long you plan to stay in the property.
What happens at the end of a fixed-rate period?
When your fixed-rate period ends, you automatically revert to the lender Standard Variable Rate (SVR), which is usually higher. It is generally recommended to remortgage to a new deal 3-6 months before your current deal expires.
What is remortgaging?
Remortgaging means switching your mortgage to a new deal, either with your current lender (product transfer) or a different lender. It is typically done when the initial deal period ends to secure a better rate or different terms.
How much does remortgaging cost?
Remortgaging costs include arrangement fees (£0-£1,999), valuation fees (£0-£500), legal fees (£150-£500), and possibly early repayment charges if still in a deal period. Some lenders offer fee-free remortgage deals or cashback incentives.
What is a mortgage in principle (MIP)?
A Mortgage in Principle (also called an Agreement in Principle) is a lender statement indicating how much they might lend you based on initial information. It is not a binding commitment but helps when making offers on properties.
What is the difference between a broker and a lender?
A mortgage broker compares deals across multiple lenders to find the best option for your circumstances. A lender is the bank or building society providing the mortgage. Brokers may charge a fee or be paid commission by the lender.
What are the different types of UK mortgage lenders?
UK mortgage lenders include high-street banks (Barclays, Lloyds, NatWest), building societies (Nationwide, Coventry), and specialist lenders. Building societies are owned by members and may offer more competitive rates to members.
How does an offset mortgage work?
An offset mortgage links your savings account to your mortgage. Instead of earning interest on savings, the balance offsets against the mortgage debt, reducing the interest charged. For example, a £200,000 mortgage with £20,000 savings only accrues interest on £180,000.
What is a buy-to-let mortgage?
A buy-to-let mortgage is for purchasing property to rent out. Requirements include a larger deposit (typically 25%+), and lending is based on expected rental income rather than personal income. Interest rates are usually higher than residential mortgages.
How is buy-to-let mortgage lending assessed?
Lenders typically require monthly rent to be at least 125-145% of the monthly mortgage payment. For example, if the mortgage payment is £1,000, the rent should be at least £1,250-£1,450. This ensures rental income covers costs with a buffer.
What are the tax implications of buy-to-let?
Mortgage interest relief on buy-to-let properties has been restricted since 2020. Landlords can no longer deduct mortgage interest from rental income; instead, they receive a 20% tax credit. Profit from rental income is taxed at your marginal income tax rate.
What is a guarantor mortgage?
A guarantor mortgage involves a family member (usually a parent) guaranteeing to make payments if the borrower cannot. The guarantor savings or property may be used as security. This helps first-time buyers with smaller deposits or lower incomes.
How does a joint mortgage work?
A joint mortgage is when two or more people apply together, combining incomes to borrow more. Common arrangements include joint tenants (equal shares) or tenants in common (specified shares). Both parties are jointly responsible for repayments.
What is the current UK housing market outlook?
The UK housing market is influenced by interest rates, inflation, government policies, and economic conditions. Keep up-to-date through sources like the Halifax House Price Index, Nationwide House Price Index, and the Office for National Statistics (ONS).

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Related Guides

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Glossary

Technical terms used in mortgage calculations explained in plain language.

Amortization
Repaying a loan over time with payments split between interest and capital.
LTV (Loan-to-Value)
The loan amount as a percentage of the property price; lower LTV mortgage rates get better rates.
Repayment Mortgage
A mortgage where each payment covers interest plus capital, clearing the loan by term end.
Interest-Only Mortgage
A mortgage where payments cover interest only; the capital must be repaid separately.
Fixed Rate
An interest rate locked for an initial period, typically 2, 3, or 5 years.
SVR (Standard Variable Rate)
The lender default rate you revert to when an introductory deal ends.
Tracker Mortgage
A variable-rate mortgage priced as the Bank of England base rate plus a fixed margin.
Overpayment
An extra payment made against the capital, usually limited to 10% per year without penalty.
ERC (Early Repayment Charge)
A fee, usually 1-5%, for repaying beyond the allowance while in a deal period.
Stamp Duty Land Tax (SDLT)
The tax on property purchases over thresholds in England and Northern Ireland.
Remortgage
Switching to a new mortgage deal, often to secure a lower rate at the end of a deal.
Help to Buy ISA
A closed scheme giving first-time buyers a 25% government bonus (up to £3,000) on savings.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

Financial Conduct Authority (FCA) MCOB RulesPrudential Regulation Authority Mortgage ConductBank of England Monetary Policy Framework

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Page Information

Last Updated:

2026-08-07

Version:

2.0.0

License:

Free to use for educational and professional purposes.